Method for allocating network resources

ABSTRACT

Network resources for a call between a calling party and a called party are allocated. The network resources for the call are reserved based on a reservation request. The network resources are reserved before any one network resource from the reserved network resources is committed. The reserved network resources for the call are committed when a called party indicates acceptance for the call.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/366,207 filed Aug. 4, 1999, now U.S. Pat. No. 6,483,912, whichclaimed the benefit of U.S. Provisional Application No. 60/104,878,filed Oct. 20, 1998; and U.S. Provisional Application No. 60/095,288,filed Aug. 4, 1998.

BACKGROUND OF THE INVENTION

The present invention generally relates to allocating network resources.More specifically, the present invention relates to reserving andcommitting network resources based on an authorized quality of service.

The known signaling architecture H.323 is an InternationalTelecommunications Union (ITU) defined standard that describes howmultimedia communications occur between terminals, network equipment andservices on local area networks (LANs) and wide area networks (WANs)that do not provide a guaranteed quality of service (such as InternetProtocol (IP) networks). Quality of service is a measure ofcommunication service quality during a call, and can include, forexample, the bandwidth, delay and latency associated with the call. Innetworks using connectionless “best effort” delivery models, the qualityof service typically is not guaranteed; the H.323 is a signalingarchitecture for such a network.

The H.323 provides a range of implementation options includinggatekeeper-routed signaling. In the H.323 standard, gatekeepers map LANaddress aliases to IP addresses and provide address lookups when needed.Gatekeepers also exercise call-control functions to limit the number ofH.323 connections and the total bandwidth used by these connections inan H.323 “zone.” Although the gatekeeper is not necessary within theH.323 standard, when a gatekeeper is present in a network, networkterminals must make use of its services. In other words, gatekeepersmaintain state information for each individual call and all callsignaling must pass through the gatekeepers.

The gatekeeper implementation of the H.323 standard, however, suffersseveral shortcomings. First, the equipment associated with gatekeepersneeds to be extremely reliable so that the gatekeeper is availablethroughout the course of the call. If the gatekeeper-related equipmentfails during a call, the call fails because the state information forthe call maintained solely at the gatekeeper is lost. Second, thegatekeeper-related equipment likely cannot scale in a cost effectivemanner because maintaining the state information and performing themessaging associated with H.323 is complex and processor intensive.Finally, theft of service is possible by bypassing the gatekeepers toplace unauthorized and unmonitored calls.

SUMMARY OF THE INVENTION

Network resources for a call between a calling party and a called partyare allocated. The network resources for the call are reserved based ona reservation request. The network resources are reserved before any onenetwork resource from the reserved network resources is committed. Thereserved network resources for the call are committed when a calledparty indicates acceptance for the call.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a network, according to an embodiment of the presentinvention.

FIG. 2 illustrates a flow chart to reserve network resources for a call,according to an embodiment of the present invention.

FIG. 3 illustrates a flow chart for performing two-phase signaling incall connection, according to an embodiment of the present invention.

FIG. 4 illustrates a flow chart for disconnecting a call, according toan embodiment of the present invention.

FIG. 5 illustrates a flow chart for translating a network address,according to an embodiment of the present invention.

FIG. 6 shows the call flow for a normal call setup, according to anembodiment of the present invention.

FIG. 7 shows an example signaling call flow for reservation of resourcesin the segment of the network between the edge routers for a voice call,according to an embodiment of the present invention.

FIG. 8 shows the call flow for a normal call termination, according toan embodiment of the present invention.

FIG. 9 shows the call flow for a call originating from a BTI butterminating in the PSTN, according to an embodiment of the presentinvention.

FIG. 10 shows the call flow for a call originating in the PSTN, butterminating in the IP telephony network, according to an embodiment ofthe present invention.

FIG. 11 shows the call flow for a normal release to the PSTN, accordingto an embodiment of the present invention.

FIG. 12 shows the call flow for a call released from the PSTN, accordingto an embodiment of the present invention.

FIG. 13 shows a call flowwhere the BTI connects to a terminatingannouncement server, according to an embodiment of the presentinvention.

FIG. 14 shows the call flow for Call Trace, according to an embodimentof the present invention.

FIG. 15 shows the call flow for changing the established callparameters, according to an embodiment of the present invention.

FIG. 16 shows the call flow for activating a per-use Call Forwardingservice, according to an embodiment of the present invention.

FIG. 17 shows the call flow for Call Forwarding—All Calls when the BTIis available, according to an embodiment of the present invention.

FIG. 18 shows the call flow for Call Forwarding—All Calls when theTerminating BTI is not available, according to an embodiment of thepresent invention.

FIG. 19 shows the call flow for Call Forwarding—Busy when BTI_(T) isavailable, according to an embodiment of the present invention.

FIG. 20 shows the call flow for Call Forwarding—Busy when the BTI isunavailable, according to an embodiment of the present invention.

FIG. 21 shows the call flow for Call Forwarding—No Answer when BTI_(T)is available, according to an embodiment of the present invention.

FIG. 22 shows the call flow for Call Forwarding—No Answer when the BTIis unavailable, according to an embodiment of the present invention.

FIG. 23 shows the call flow for Caller ID/Calling Name Delivery CallFlow, according to an embodiment of the present invention.

FIG. 24 shows a call flow for Call Waiting, according to an embodimentof the present invention.

FIG. 25 shows the call flow for the simple Three-Way Calling alternativewith bridging in BTI_(O), according to an embodiment of the presentinvention.

FIG. 26 illustrates the first steps of a three-way call, according to anembodiment of the present invention.

FIG. 27 shows the sequence of signaling messages exchanged in theconversion of two separate calls into one three-way call, according toan embodiment of the present invention.

FIG. 28 shows the call flow for Three-way Calling Bridge in Network CallFlow—Hangup of Host, according to an embodiment of the presentinvention.

FIG. 29 shows the call flow for Three-way Calling Bridge in Network CallFlow—Hangup of Participant, according to an embodiment of the presentinvention.

FIG. 30 shows the call flow for Call Transfer With Consultation servicewhen the host disconnects, according to an embodiment of the presentinvenion.

FIG. 31 shows the call flow for Call Transfer Without Consultationservice, according to an embodiment of the present invention.

FIG. 32 shows the call flow for Return Call, according to an embodimentof the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention relate to a communications systemhaving a combination of different types of networks, such as a datanetwork(s) (based on, for example, packet switching), a telephonenetwork(s) (such as the Plain Old Telephone Network (PSTN)), and/or acable network(s). Such a communications system can include intelligentend-terminals that allow a service provider to provide various types ofservices involving the different types of networks and to exploit thecapabilities of the end-terminals. For example, packet telephony can beimplemented in embodiments of the present invention where voice can bereceived and transmitted by a telephone or a communication device (suchas a personal computer) connected to the data network via a cablenetwork.

Embodiments of the present invention relate to call authorization, callsignaling, network resource management and end-to-end signaling betweencommunication devices (e.g., telephones, personal computers, etc.).Existing telephone services with a service quality consistent withcurrent standards can be supported while a broader range ofpacket-enabled communications services can also be supported.Embodiments of the present invention allow pricing and billing ofcommunications services to differ based on the differences in servicequality (e.g., bandwidth, delay and/or latency) for the various calls.

Embodiments of the present invention also allow the intelligentend-points to participate in supporting features of the providedservices. These intelligent end-points can be, for example,telephony-capable computers and gateways that interface conventionaltelephones to the data network. By exploiting the intelligence of theseend-points in supporting the features of provided services,functionality (e.g., tasks associated with signaling) historicallymaintained solely by the network can be efficiently divided among thecommunication network entities and the intelligent end-points connectedto the communication network.

In addition, embodiments of the present invention protect against theftof service, and minimize the cost and complexity associated withproviding reliable service. Unlike known telephone networks, embodimentsof the present invention do not require high-availability networkservers that maintain the state of each individual call. Rather,embodiments of the present invention can maintain state information onlyin the edge routers and the end-points that are directly involved in aparticular call.

The following discussion is separated into sections for clarity. First,a system overview of a communication network, according to an embodimentof the present invention, is discussed in Section 1 entitled “SysstemOverview”. Then, separate aspects of embodiments of the presentinvention are considered: Section 2 entitled “Two-Phase ResourceReservation”, Section 3 entitled “Two-Phase Signaling”, Section 4 “GateCoordination on a Per-Call Basis”, Section 5 entitled “Network AddressTranslation”, Section 6 entitled “Simulating Destination Ring Back”.Finally, Section 7 entitled “Protocol Description” details the protocolsfor the signaling messages and Section 8 entitled “SignalingArchitecture Call Flows” describes the call flows for the signalingarchitecture both of which are applicable to the various aspects ofembodiments of the present invention.

1. System Overview

FIG. 1 illustrates a network according to an embodiment of the presentinvention. Network 10 includes communication network 100 which isconnected to gate controller 110 and gate controller 111, network edgedevices 120 and 121, and telephone network gateway 130. Gate controllers110 and 111 are connected to database storage 140 and 141, respectively.Network edge devices 120 and 121 are connected to access networks 150and 151, respectively. Access networks 150 and 151 are connected tonetwork interface units 160 and 161, respectively. Network interfaceunits 160 and 161 are connected to telephone interface units (TIUs) 170and 171, respectively, and communication devices 180 and 181,respectively. TIUs 170 and 171 are connected to telephones 190 and 191,respectively. Telephone network gateway 130 is connected to telephonenetwork 135 which, in turn, is connected to telephone 192.

Communication network 100 can be a network that supports, for example,Internet Protocol (IP) signaling, IP media transport, and/orasynchronous transfer mode (ATM) media transport. Access networks 150and 151 can be networks of wires or fibers capable of carrying voiceand/or data transmissions. The telephone network 135 can be, forexample, the Plain Old Telephone System (PSTN).

Network interface units 160 and 161 can be, for example, cable modemsdesigned for use on a television coaxial cable circuit. Networkinterface units 160 and 161 allow communication devices 180 and 181,respectively, to connect to access networks 150 and 151, respectively.Network interface units 160 and 161 also allow TIUs 170 and 171,respectively (and in turn telephones 190 and 191, respectively), toconnect to access networks 150 and 151, respectively.

Network edge devices (NEDs) 120 and 121 are devices located at the edgeof the communication network 100 that connects the communication network100 to the access networks 120 and 121, respectively. The network edgedevices can be, for example, routers or bridges or similar equipmentthat can connect communication network 100 to access networks 150 and151. Because NEDs 120 and 121 can be specifically implemented as, forexample, routers at the network edge, these units are also referred toherein as edge routers (ERs).

Network edge devices 120 and 121 can implement resource management andadmission control mechanisms that allow the communication network 100 toprovide assurances of bounded per-packet loss and delay required toassure an authorized quality of service for a call. In other words,network edge devices (e.g., network edge devices 120 or 121) can obtainauthorization from an associated gate controller (e.g., gate controller110 or 111, respectively) on a call-by-call basis before providingaccess to, for example, enhanced quality of service across thecommunication network. Said another way, the network edge devices canensure that enhanced quality of service for a call of a particular partyhas been authorized and for which usage accounting is being done.Network edge devices can generate accounting records for calls becausethese devices track the resource usage within the communication network100 for the calls. Network edge devices can also implement NetworkAddress Translation to support address privacy for called paries and/orcalling parties, as described more fully below.

TIUs 170 and 171 are gateways between telephones and packet-carryingnetworks, such as access networks 150 and 151 and communication network100. TIUs 170 and 171 can digitize, compress and packetize voice signalsfrom telephone 190 and 191, respectively, to convert analog voice intodata packets for transport over the communication network 100, and viceversa. TIUs 170 and 171 can be, for example, a simple stand-alonetelephony device that incorporates the broadband interface, a high-speeddata cable modem that incorporates the interface unit (i.e., TIUs andtheir associated network interface units can be combined into a singledevice), or an advanced digital set-top box that incorporates thebroadband interface. TIUs 170 and 171 can be for example broadbandinterfaces for telephones; consequently, these units are also referredto herein as broadband telephony interfaces (BTIs).

TIUs contain sufficient processing and memory to perform signaling andcall control functions. More specifically, TIUs 170 and 171 each includea processor and is capable of detecting changes in state information(e.g., hook state detection), collecting dialed digits (e.g., dual-tonemultifrequency (DTMF) signals), and participating in the implementationof telephone features for telephones 190 and 191, respectively. TIUs 170and 171 can also participate in end-to-end capability negotiation asdescribed below.

Note that the term “end-to-end” refers the association between two endpoints for a call. For example, where a call involves a calling partyand a called party using telephones, the end-to-end association for thecall can be between the two telephony interface units. Thus, end-to-endmessages for example would include messages originating at one telephoneinterface unit and terminating at the other telephony interface unitwhere the messages are opaque to other network entities that merelyforward the messages (possibly after performing network addresstranslation as described below). For example, end-to-end messages can berouted between telephone interface units with messages being forwardedby the network edge devices and without the message being routed throughthe gate controllers. Alternatively, for example, where a call involvesa calling party using a telephone and a called party using acommunication device (such as a personal computer), the end-to-endassociation for the call can be between the calling party telephonyinterface unit and the called party network interface unit.

TIUs can maintain information for calls while in progress, therebyimplementing certain service features locally. For example, call waitingcan be implemented locally, by detecting hook flash and controlling theactive call. Similarly, return call can be implemented locally byretaining state information in the TIUs about the most recent calls.

Note that TIUs 170 and 171 are considered to be “untrusted” devices inthe sense that the TIUs can operate locally-stored software and are notnecessarily under the direct control of the service provider (e.g., theentity operating the communication network 100). Because the TIUs areuntrusted devices, information passed to the TIUs can be first encryptedbefore it is given to the TIUs to guarantee privacy. For example, stateinformation can be passed from the gate controllers 110 and/or 111 tothe TIUs which store the state information for their later use (therebyavoiding the need to maintain state information for a call at the gatecontrollers) by first encrypting the state information; the stateinformation retrieved from the TIUs can be verified subsequently viaknown encryption techniques.

In addition to encrypting the state information for the TIUs tomaintain, a cryptographic hash function can be applied to the stateinformation to detect the integrity of the state information (i.e.,detect whether the state information has been altered by an untrustedentity). By applying a cryptographic hash value to the stateinformation, a hash value is produced which can be sent to andmaintained by the TIUs. As a result, when the state information isretrieved from a TIU, the cryptographic hash function can be applied tothis retrieved state information; if the same hash value is produced,then the retrieved state information has not been altered at, forexample, the TIU. The cryptographic hash functions can be, for example,a modification detect codes (MDCs) or message authentication codes(MACs).

Gate controllers 110 and 111 are adjunct platforms that have access toauthentication databases and customer profile information on databasestorage 140 and 141, respectively. Gate controllers 110 and 111implement a set of service-specific control functions to supportcommunication services, such as authentication and authorization, numbertranslation and call routing, service-specific admission control, andsignaling and service feature support.

The gate controllers can authenticate signaling messages and authorizerequests for service so that communication services and certain servicefeatures are only provided to authorized subscribers. In other words,upon receiving a setup request message from a calling party, the gatecontroller can authenticate the identity of the calling party andauthorize the service sought by the calling party.

The gate controllers can translate dialed telephone numbers tocommunication network addresses (such as, for example, IP addresses)based on call routing logic. For example, an originating gate controller(e.g., gate controller 110) can translate a dialed telephone number to acommunication network address associated with the terminating gatecontroller (e.g., gate controller 111). The terminating gate controllercan subsequently translate the communication network address to theterminating end-point (e.g., BTI 171) to which the call should berouted. In an alternative embodiment, a single dial telephone number canbe mapped to multiple communication network addresses, for example, toallow the signaling and media end-points associated with a call to bedistinct.

The gate controllers can implement a broad range of service-specificadmission control policies for the communication services. For example,the gate controllers can provide precedence for particular call (e.g.,911 emergency calls). The gate controllers can perform admission controlto implement overload control mechanisms similar to those used in theconvention telephone network (e.g., telephone network 135), for example,to restrict the number of calls to a particular location or to restrictthe frequency of call setup to avoid signaling overload. Thesemechanisms can be invoked either dynamically or under administrativecontrol.

The gate controllers can perform signaling and service feature supportwhere the service features cannot be supported solely by the TIUs. Forexample, certain service features such as call transfer require changingthe end-points participating the calls; in such a case, the gatecontrollers change the gate parameters because call transfer requiresreauthorization by the gate controllers. Service features that depend onthe privacy of the calling information, such as caller-ID blocking, areimplemented by the gate controllers. In addition, service features thatrequire users to receive a consistent view of feature operation evenwhen a TIU is inoperative are implemented by the gate controllers. Forexample, the gate controllers can control call forwarding when a TIU fora call is inoperative.

Gate controllers can be organized in domains where each gate controlleris associated with a set of TIUs and the network edge devices that servethose TIUs. Although the TIUs are not trusted entities, a trustrelationship exists between an network edge device and its associatedgate controller because the gate controller acts as a policy servercontrolling when the network edge device can provide enhanced quality ofservice. A trust relationship can also exist between gate controllers.

A gate controller can act as a simple transaction server so that afailure of a gate controller does not affect associated calls that arein process. In one embodiment, a gate controller domain can include aprimary and a secondary gate controller. If the primary gate controllerfails, only calls in a transient state are affected (i.e., calls thatare being established including, for example, where network resourcesare being allocated). The TIUs associated with those affected calls in atransient state will try to be established on the secondary gatecontroller after a time-out period has elapsed. All active calls (i.e.,calls in progress) are unaffected by the failure of a primary gatecontroller because the gate controller does not retain state informationfor these stable, active calls. As a result, gate controllers easily andefficiently scale as more gate controllers for the communication networkare required.

Telephone network gateway 130 can include a combination of a trunkinggateway (not shown) and a signaling gateway (not shown). The trunkinggateway can convert between a data format used on the data network 100and the pulse code modulation (PCM) format typically used fortransmission over the telephone network 135. The signaling gateway canprovide signaling internetworking between signaling protocols ofembodiments of present invention described below and conventionaltelephony signaling protocols such as ISUP/SS7 (i.e., IntegratedServices Digital Network User Part/Signaling System 7). In analternative embodiment, a media gateway control protocol can be used tocontrol the operation of a media gateway separate from a signalinggateway.

Although not shown in FIG. 1, additional network entities (not shown)can be included in the network 10. For example, the gate controllers canuse other servers to implement the authorization or the translationfunctions. Similarly, three way calling can be supported using audiobridges in the network 10.

Note that although a limited number of network entities are shown inFIG. 1 for simplicity of presentation, other network entities can beincluded in network 10. For example, although only a sole networkinterface unit (e.g., a cable modem) is shown connected to a solenetwork interface unit, multiple network interface units are likelyconnected to each access network. Similarly, although only a few networkedge devices, a few gate controllers and a sole telephone networkgateway are shown connected to the communication network 100, many suchdevices can be connected to the communication network 100. Many othervariations to the network 10 shown in FIG. 1 are possible.

2. Two-Phase Network Resource Reservation

In embodiments of the present invention, network resources for a callbetween a calling party and a called party are allocated. The networkresources for the call are reserved based on a reservation request. Thenetwork resources are reserved before any one network resource from thereserved network resources is committed. The reserved network resourcesfor the call are committed when a called party indicates acceptance forthe call.

The term “network resources” is used herein as the facilities of acommunications network required for a call and any auxiliary servicesassociated with that call. Network resources can include, for example,the capabilities or capacities of equipment within the communicationsnetwork needed to establish and maintain a call at an appropriatequality of service. The equipment within the communications network caninclude, for example, routers, bridges and gateways within thecommunications network.

The called party “indicates acceptance” for the call in a number ofways. For example, where the called party is using a telephone 190, thecalled party can indicate acceptance for the call by picking up thetelephone hand set thereby causing an off-hook condition. Where thecalled party is using a communication device 181 (e.g., a personalcomputer), the called party can indicate acceptance by making anappropriate selection with the communication device 181 that initiateshandshake signaling (i.e., a personal computer equivalent for anoff-hook condition). Where the called party has an answering machine,the answering machine timer can expire to connect the call.

Network resources are “reserved” in the sense that the network resourcesrequired for a particular call can be identified before the called partyis actually connected to the calling party. These network resources canbe reserved through the appropriate signal messages collectivelyreferred to herein as a “reservation request”. After the appropriatenetwork resources have been reserved based on the reservation request,these network resources are committed when the called party indicatesacceptance for the call. By committing the network resources only whenthe called party indicates acceptance for the call, the accounting forthe call can, for example, accurately track the time of the actual callwhile excluding the time of the call setup.

Network resources are “committed” in the sense that an available networkresource operates such that the voice information between the callingparty and the called party is transported. Before the network resourcesare committed, the network resources are allocated for the call but arenot configured to actually carry the voice information for the call. Bycommitting the reserved network resources once the called partyindicates acceptance for the call, the network resources are notwastefully configured before they are actually needed. This can beparticularly relevant for portions of the communication network whereresources are limited, such as, for example, the upstream resourceswithin the cable network.

The term “quality of service” is used herein to include, but not limitedto, the measure of telecommunication service quality provided during acall. The quality of service can be specified by a calling party, acalled party or the service provider of the communications network, orany combination thereof. In other words, the quality of service is“authorized” in the sense that the calling party and/or the called partyspecify a quality of service for the call and the service provider canverify the specified quality of service for the call. For example, acalling party transferring data (e.g., rather than transferring solelyvoice) may subscribe for a service with a quality of service having alarge bandwidth and small latency; in such an example, a serviceprovider can verify the service subscription for the particular qualityof service associated with the call for that particular calling party.

FIG. 2 illustrates a flow chart to reserve network resources for a call,according to an embodiment of the present invention. FIG. 2 is asimplified view of the connection process to better illustrate thetwo-phase allocation of network resources. This process is in two phasesin the sense that network resources are first reserved and thencommitted in separate and distinct phases. In other words, networkresources are reserved first; once the reservation process is complete,then the reserved network resources can be committed. Other aspects ofthe overall process will be described in further detail in othersections below.

Note that components of the communications networks shown in FIG. 1 arereferred to in FIG. 2 for convenience with the shorthand notation:originating TIU 170 (TIU_(O)), originating network edge device 120(NED_(O)), originating gate controller 110 (GC_(O)), terminating gatecontroller 111 (GCT), terminating network edge device 121 (NED_(T)), andterminating TIU 171 (TIU_(T)).

At step 210, a setup message for a call between a calling party and acalled party is sent from the originating TIU 170 to the originatinggate controller 110 and the terminating gate controller 111. Forexample, upon receiving the setup message at the originating gatecontroller 110, the setup message (possibly modified with additionalinformation) can be forwarded to the terminating gate controller 111through communication network 100. In one embodiment, the setup messagecan be, for example, in the form of the SETUP message described below inSection 7 entitled “Protocol Description”.

At step 220, a gate for the call is established at the terminatingnetwork edge device 121 upon receiving the setup message fromterminating gate controller 111. A “gate” is a call-admission controlmechanism that uses, for example, known packet filters at the edgerouters. At step 230, another gate for the call is established at theoriginating network edge device 120. In one embodiment, the gates canhave associated time limits on the gate duration; such a features canallow the calls to be limited where, for example, the calls areestablished with a pre-paid calling card that has a limited amount ofcalling time that is pre-paid.

Note that by establishing the gates at the originating and terminatingnetwork edge devices rather than at the corresponding gate controllers,the state information for the call is maintained at a network entitythrough which the call is routed. In other words, state information fora call can be maintained without maintaining the state information at agate controller. Consequently, if a gate controller fails after thegates have been established for a call, the call can be maintained. Theestablishment of gates for a call are discussed more fully below in theSection 4 entitled “Gate Coordination on a Per-Call Basis”.

At step 240, a reserve message is sent from the originating TIU 170 tothe originating NED 120. At step 250, a reserve message is sent from theterminating TIU 171 to the terminating NED 121. The reserve messagessent by the originating TIU 170 and terminating TIU 171 are a part ofthe reservation process where an allocation of network resources isrequested but the network resource need not yet be assigned orcommitted. Allocating the network resources includes the verifying thatthe quality of service desired by a TIU is no greater than the qualityof service authorized by the corresponding gate controller; the gatecontroller authorizes a quality of service for a call using theauthentication databases and customer profile information on theassociated database storage (e.g., database storage 140 and 141).

To provide telephone-grade service over network 10, the network 10 canprovide bounded per-packet loss and delay for the voice packets of acall by performing active resource management both in the access network150 and 151, and communication network 100. Because the network edgedevices (e.g., NEDs 120 and 121) within the connection path for a callmay have capacity constrained links, reservation requests for a call(and any associated messages) are forwarded end to end, thereby ensuringthat network resources are available end to end. In one embodiment,because the access networks 150 and 151 may be capacity constrained (atleast in the upstream direction), resource management is performed on aper-call basis for the access networks 150 and 151.

Resource management in the communication network 100, however, can beperformed on a per-call basis or on a coarse-grained resource basis(i.e., resources within the communication network 100 can be reservedfor multiple calls at a given time). Resource management within portionsof the communication network 100 may be performed on a per-call basisbecause some network edge devices with the communications network 100may not have sufficient processing capacity to process a large number ofreservation messages typical for high volume call traffic.Alternatively, resource management within portions of the communicationnetwork 100 may be performed on a multiple-call basis if these portionsof the communication network 100 are adequately provisioned (i.e.,sufficient capacity has been reserved by a multiple-call reservation);in such cases, network edge devices within these portions ofcommunication network 100 need not perform per-call admission control.Consequently, in an embodiment of the present invention, some networkedge devices do per-flow admission control to interpret reservationrequests while other network edge devices that are in capacity-richregions of the data network 100 are provisioned to simply forward thesemessages without interpretation.

Embodiments of the present invention can perform resource reservation inthe communication network 100 in a uni-directional manner which therebycompensates for routing asymmetries. Thus, when the originating TIU 170sends a reservation request to the originating NED 120 and when theoriginating TIU 170 receives back an acknowledgment for the reservationrequest, two aspects are of the connection are confirmed. First,adequate bandwidth for the call is available in both directions over theaccess networks 150 and 151. Second, adequate bandwidth for the call isavailable over the communication network 100.

Steps 210 through 240 describe the process of reserving the networkresources. At this point, the network resources to be used for the callare reserved, but none of these network resources are yet committed.

At step 250, end-to-end messages are exchanged between the originatingTIU 170 and the terminating TIU 171. As previously discussed above, theterm “end-to-end” refers the associated between two end pointsassociated with a call. So, where a call involves a calling party and acalled party using telephones, the end-to-end association for the callcan be between the two telephony interface units; thus, end-to-endmessages would include messages originating at one telephone interfaceunit and terminating at the other telephony interface unit.

The end-to-end messages can include, for example, a ring message fromthe originating TIU 170 to the terminating TIU 171, a ring back messagefrom the terminating TIU 171 to the originating TIU 170, and a connectmessage from the terminating TIU 171 to the originating TIU 170. Thering message can signal the terminating telephone 191 to ring therebyindicating an incoming call. The ring back message can signal theoriginating TIU 170 that the terminating telephone 190 is ringing. Theconnect message can signal to the originating TIU 170 that the calledparty has indicated acceptance for the call by, for example, goingoff-hook. Note that these end-to-end messages can be routed between theoriginating TIU 170 and the terminating TIU 171 without being routedthrough the originating gate controller 110 or terminating gatecontroller 111.

At step 270, upon the calling party and the called party being connected(e.g., upon an off-hook condition by the called party and a connectmessage being sent), a commit message is sent from the originating TIU170 to the originating NED 120 and from the terminating TIU 171 to theterminating NED 121.

At step 280, upon receiving the commit message at the originating NED120, the gate established at the originating NED 120 in step 230 isopened. Similarly, at step 290, upon receiving the commit message at theterminating NED 121, the gate established at the terminating NED 120 instep 220 is opened. At this point when the gates are opened at theoriginating NED 120 and the terminating NED 121, the reserved networkresources are committed. The commit process can include a verificationby the NED that the actual quality of service sought by the associatedTIU is no greater than the quality of service reserved during thereservation process.

The gate at the originating edge router and the gate at the terminatingedge router for each call are opened almost simultaneously (e.g., withina few hundred milliseconds of each other) because, under normaloperating conditions, the calling party and the called party sendrespective Commit message to their respective network edge devicessubstantially simultaneously. Similarly, under normal operatingconditions, the calling party and the called party end the call and sendrespective release messages to their respective network edge devicessubstantially simultaneously. Gate coordination prevents billing forincomplete calls and prevents theft of service by two colluding BTIs.

By separating the reservation process from the commit process,embodiments of the present invention advantageously ensure that networkresources are available before actually ringing the far-end telephone(e.g., the telephone of the called party). This, of course,advantageously ensures that usage recording is not initiated until thefar-end telephone goes off hook. Consequently, call billing excludescalls that are not completed (e.g., where the called party does notanswer) and excludes the portion of calls that occur before the calledparty answers.

Although FIG. 2 describes an embodiment for reserving network resourceswhere the calling party and the called party were using telephones 190and 191, respectively, through TIUs 170 and 171, respectively, theprocess can be analogized for a calling party and/or called party usinga communication device 180 and/or 181, respectively.

Note that the state information for a call can be maintained withoutmaintaining the state information at a gate controller. From theperspective of the originating gate controller, a gate setup message fora call (e.g., a GATESETUP message described in Section 7 below) isreceived through a network edge device connecting a trusted network toan untrusted network. The state information for the call (e.g.,contained within a GATEALLOC message described in Section 7 below) isformatted at the gate controllers based on the setup message for thecall. The state information for the call is sent to the originatingnetwork edge device without maintaining the state information at theoriginating gate controller and at the terminating network edge devicewithout maintaining the state information at the terminating gatecontroller.

Note that the term “maintained” as used herein in reference to the stateinformation is intended to include storing and using the stateinformation while the call is being establishing, the call is inprogress and the is being released. Although the state information maybe temporarily stored at the gate controllers, the state information isnot maintained at the gate controller because the gate controllers donot do not use the state information (e.g., for call processing) whilethe call is being establishing, the call is in progress and the call isbeing released. In fact, the gate controllers need not stored the stateinformation after the state information has been provided to the networkedge routers because the state information for the call is accessed atthe gate controllers, not the gate controllers.

3. Two-Phase Signaling

In embodiments of the present invention, signaling messages areexchanged for a call between a calling party to a called party in twophases. The signaling messages are exchanged in two phases in the sensethat the messages for setting up the call are exchanged in one phase andthe messages for connecting the call are exchanged in a separate anddistinct second phase. By separating the messages for setting up thecall from the messages for connecting the call, the later messages canbe exchanged end to end without being routed through the gatecontrollers that set up the call.

Note this concept of two-phase signaling is distinct from the concept oftwo-phase network resource reservation in the sense that the two-phasesignaling can be performed in combination with or independent of thetwo-phase network resource reservation. In other words, when done incombination, the messaging for the two-phase signaling can beinterleaved with the messaging for the two-phase network resourcereservation; when done independently, the messages for each can bedistinct. The two-phase network resource reservation relates toreserving network resources without committing them, then committingthose reserved resources. The two-phase signaling relates to performingsignaling to set up the call, then once the call is setup (e.g., therebyconfirming the authoried quality of service), exchanging end-to-endmessaging.

A setup message having a destination address is forwarded from thecalling party to the called party. A setup acknowledgment message isreceived at, for example, a gate controller from the called party if thedestination address corresponds to the called party. The received setupacknowledgment message is sent to the calling party. The calling partyand the called party exchange end-to-end messages if the calling partyreceived the forwarded setup acknowledgment message and if at least onefrom the group of the called party and the calling party sent a reservemessage to an associated network edge device.

FIG. 3 illustrates a flow chart for performing two-phase signaling incall connection, according to an embodiment of the present invention. Atstep 310, the calling party goes off-hook and dials a telephone numberof the called party. For convenience, FIG. 3 will be discussed where thecalling party is using telephone 190 and the called party is usingtelephone 191. Of course, any number of arrangements are possible, suchas the calling party using communication device 180. At step 320, theoriginating TIU 170 collects the dialed digits.

At step 330, the originating TIU 170 sends a setup message to theoriginating gate controller 110. The setup message can be sent throughnetwork interface unit 160, access network 150, NED 120 andcommunication network 100. In one embodiment, the setup message can be,for example, in the form of the SETUP message described below in Section7 entitled “Protocol Description”.

At step 340, the setup message is forwarded from the originating gatecontroller 110 to the terminating gate controller 111. At step 350, thesetup message is forwarded from the terminating gate controller 111 tothe terminating TIU 171. (After receiving the setup message, theoriginating gate controller 110 and the terminating gate controller 111,can establishe a gate at the originating NED 120 and a gate at theterminating NED 121 as described in Section 2 above.)

At step 360, if the destination address of setup message corresponds tothe terminating TIU 171, a setup acknowledgment message is sent to theTIU 170. The setup acknowledgment message can be sent, for example,through terminating gate controller 111 and originating gate controller110. In one embodiment, the setup acknowledgment message can be, forexample, in the form of the SETUPACK message described below in Section7 entitled “Protocol Description”.

At step 370, the network resources for the call are reserved. Asdescribed above in Section 2 entitled Two-Phase Network ResourceReservation, a reserve message is sent from the originating TIU 170 tothe originating NED 120 and from the terminating TIU 170 to theterminating NED 121 when an allocation of network resources is requestedbut the network resource need not yet be assigned or committed.

At steps 380 through 395, end-to-end messages are exchanged between theoriginating TIU 170 and the terminating TIU 171 if the calling partyreceived the setup acknowledgment message sent to the originating TIU170 in step 360 and if the calling party or the called party sent areserve message to its NED. In other words, end-to-end messages relatingto the connection of the call are exchanged only after the reservationmessages have been exchanged and the reservation process is complete.This ensures that service is only provided to calling and called partiesthat have been authorized and authenticated for the call. This alsoensures that the call is established for a specifically authorizedquality of service and that the call is billed appropriately.

At step 380, a ring message is sent from the originating TIU 170 to theterminating TIU 171. The ring message can signal the terminatingtelephone 191 to ring thereby indicating an incoming call.

At step 390, a ring back message is sent from the terminating TIU 171 tothe originating TIU 170. The ring back message can signal theoriginating TIU 170 that the terminating telephone 190 is ringing.

At step 395, a connect message is sent from the terminating TIU 171 tothe originating TIU 170. The connect message can signal to theoriginating TIU 170 that the called party has indicated acceptance forthe call by, for example, going off-hook.

These end-to-end messages can be routed between the originating TIU 170and the terminating TIU 171 without being routed through the originatinggate controller 110 or terminating gate controller 111 because stateinformation for the call can be maintained without maintaining it at thegate controllers 110 and 111. In addition, these end-to-end message canbe routed through NEDs 120 and 121 opaquely.

Note that by separating the signaling for a call relating thereservation process and relating to connect process, the concept of thetraditional dedicated phone line for a telephone user can be replacedwith a process that authenticates the calling party and called party,and authorizes a desired quality of service on a per-call basis. Inother words, only authenticated users reserved network resources for anauthorized quality of service before these network resources areconnected. Consequently, calls having varying qualities of service canbe provided and appropriately billed on a call-by-call basis.

Furthermore, by separating the signaling for a call into signalsrelating to the reservation process and signals relating to the connectprocess, the gate controllers are involved in the signaling processwhere only needed: during the reservation process. After the reservationprocess is complete, the originating and terminating gate controllerspass the state information for the call to, for example, the originatingand terminating TIUs without maintaining the state information at thegate controllers. The gate controllers no longer need be involved in thecall and messaging related to the connection process can be sentend-to-end without being routed through the gate controllers. In otherwords, the gate controllers are involved only during the initial startof the call but not during the call duration. This results in areduction of the message load by, for example, approximately a factor ofthree. Consequently, the amount of memory need in the gate controllersis greatly reduced. Moreover, the gate controllers can be constructedwithout the typically stringent requirements for reliability.

4. Gate Coordination on a Per-Call Basis

As discussed in the preceding section, reserved network resources can becommitted upon the originating and terminating network edge devicesreceiving commit messages indicating that the call has been connected.At this point, gates associated with a call between a calling party anda called party can be opened in a coordinated fashion. A timerassociated with a first gate opened at an originating network edgedevice is initiated. A first gate open message is sent from theoriginating network edge device to the terminating network edge device.The first gate at the originating network edge device is released if thetimer expires before at least one from the group of: (1) anacknowledgment based on the sent first gate open message is receivedfrom the terminating network edge device, and (2) a second gate openmessage is received at the originating network edge device from theterminating network edge device after the terminating network edgedevice has opened a second gate associated with the called party.

At step 400, a timer associated with a gate at the originating NED 120is initiated upon receiving a commit message from the originating TIU170. At step 410, a timer associated with a gate at the terminating NED121 is initiated upon receiving a commit message from the terminatingTIU 171. As described above in Section 2 entitled “Two-Phase NetworkResource Reservation”, the commit message is sent from a TIU to theassociated NED upon the called party indicating an acceptance for thecall (e.g., by a connect message being sent from the terminating TIU tothe originating TIU). The order steps 400 and 410 depends on the orderin which the NEDs receive the commit messages from their associatedTIUs.

At step 420, a gate open message is sent from the originating NED 120 tothe terminating NED 121. At step 430, a gate open message is sent fromthe terminating NED 121 to the originating NED 120. In one embodiment,the setup acknowledgment message can be, for example, in the form of theGATEOPEN message described below in Section 7 entitled “ProtocolDescription”. The order in which steps 420 and 430 are performed dependson the order in which steps 400 and 410 are performed. A gate openmessage is sent from one NED to the other NED to notify that other NEDwhen a gate for the call has been opened.

At step 440, a gate open acknowledgment message is sent from originatingNED 120 to terminating NED 121 upon the originating NED 121 receivingthe gate open message sent during step 430 by terminating NED 120. Atstep 450, a gate open acknowledgment message is sent from terminatingNED 121 to originating NED 120 upon the terminating NED 120 receivingthe gate open message sent during step 420 by originating NED 120. Inone embodiment, the setup acknowledgment message can be, for example, inthe form of the GATEOPENACK message described below in Section 7entitled “Protocol Description”. The order in which steps 440 and 450are performed depends on the order in which the gate open acknowledgmentmessage are received.

At conditional step 470, a determination is made as to whether the timerfor the gate at the originating NED 120 expired before (1) theoriginating NED 120 received the gate open acknowledgment message fromthe terminating NED 121, or (2) the originating NED 120 received thegate open message from the terminating NED 121. If the timer expiredbefore either condition is satisfied, then the process proceeds to step475 where the gate at the originating NED 120 is closed and released. Ifthe timer did not expire before either condition is satisfied, then theprocess proceeds to step 477 where the gate at the originating NED 120is allowed to remained open.

At conditional step 480, a determination is made as to whether the timerfor the gate at the terminating NED 121 expired before (1) theterminating NED 121 received the gate open acknowledgment message fromthe originating NED 120, or (2) the terminating NED 121 received thegate open message from the originating NED 120. If the timer expiredbefore either condition is satisfied, then the process proceeds to step485 where the gate at the terminating NED 121 is closed and released. Ifthe timer did not expire before either condition is satisfied, then theprocess proceeds to step 487 where the gate at the terminating NED 121is allowed to remained open.

A gate is “closed” in the sense that the call is no longer activealthough the gate for the call remains established for possible lateruse. For example, in a call having a call waiting feature, a first partycan be connected to two other parties and two gates (one per call) willbe established at the network edge device associated with the firstparty. In such a case, as the first party switches between the calls thetemporarily inactive call will have an associated gate that is closed;this closed gate can be reopened upon the call being reactivated.

A gate is “released” in the sense that the call is no longer active andthe gate for the call is deleted from the associated network edgedevice. In such a case, for a call to be started, the entire networkresource reservation process and commit process (see, e.g., thediscussed relating to FIG. 2) have to be repeated.

The timer at a gate ensures that the other gate related to the call isalso opened within the timer period so that billing for the call isaccurate and so that theft of service can be prevented. Without suchgate coordination, either a service provider could bill a party for acall where only one gate was opened (even if the calling party was notconnected to the called party) or a service provider could besusceptible to theft of service for a call where only one gate wasopened. Considering the latter, theft of service could occur withoutgate coordination, for example, by two colluding TIUs: where theoriginating TIU can initiate a call and only the terminating TIU sends alocal commit message, the single gate would not be released for up toseveral minutes because the far-end telephone could be ringing; theoriginating BTI could then steal service during this time. By sendingthe gate open message from the network edge device with an open gate tothe network edge device without a corresponding peer gate, the secondgate for the call is sure to be established even if a commit message isnot received from the associated TIU (as could be the case if a theft ofservice was attempted).

Gate coordination can also be performed at the end of a call. Just as agate open message and a gate open acknowledgment message is sent to thenetwork edge device where the peer gate is established, a gate closemessage and a gate close acknowledgment message can be sent upon a gateclosing to the network edge device where the peer gate is open. In otherwords, when a call is ended by either the calling party or the calledparty, the party ending the call has its gate closed and the peer gateis informed of the closure so that the peer gate is also closed. Anexample of the message exchange for a gate closing is shown in FIG. 8and the associated discussion in Section 8 entitled “SignalingArchitecture Call Flows”.

By coordinating the gate closings, again theft of service by amalfunctioning or malicious TIU can be prevented. Consider the casewhere the originating TIU 170 calls terminating TIU 171 and pays for thecall. If either the calling party or the called party end the call, thegates at both the originating NED 120 and the terminating NED 121 needto be closed. Because the originating TIU 170 is being billed for thecall, the calling party has an incentive to issue a release message toclose the gate at the originating NED 120. The terminating TIU 171,however, cannot be trusted to send the release message to close the gateat the terminating NED 121. A gate close message sent from theoriginating NED 120 can close the gate at the terminating NED 121 toprevent the terminating TIU 171 from placing another call and havingthat call billed to the party associated with TIU 170.

5. Network Address Translation

Because the TIUs are untrusted entities, any information that a callingparty or a called party desires to keep private, such as caller IDinformation or address information, should be accessible to the network10 but not to other untrusted entities. This section describes the useof network address translations and encryption techniques that allowgate controllers to send state information to TIUs where it ismaintained in a form that renders the private information opaque.

In one embodiment, a call between a calling party and a called party isconnected. Information associated with the call is sent from the callingparty to the called party without the called party receiving a sourceaddress that indicates at least one from the group of a logical identityof the calling party and a geographical identity of the calling party.

The term “logical identity” is used to herein to include, for example,any aspect of the source address or destination address that indicatesthe specific identity of a calling party or the called party. The term“geographic identity” is used to herein to include, for example, anaspect of the source address or destination address that indicates theparticular geographic location of a calling party or called party. Evenwhere a network address has been modified or altered to protect thelogical identity of a calling party or called party, the remainingaspects of the network address can reveal the general geographiclocation of the party. In an embodiment of the present invention,information is sent from one party to another party without revealingeither the logical identity nor the geographic identity of a party.

FIG. 5 illustrates a flow chart for translating a network address,according to an embodiment of the present invention. At step 500,packets having the source address and the destination are sent from theoriginating TIU 170 through the originating network interface unit 160towards the originating NED 120. The source address and the destinationaddress locally identify the calling party and the called party,respectively. These addresses are “local” in the sense that they areassociated with particular portions of networks (also referred to hereinas “address domains”), such as portions of the access network 150 and/orcommunication network 100 and/or other access networks (not shown inFIG. 1). These local addresses are not sent outside of their resepectiveaddress domains. To send packets outisde of the address domain, thedestination needs to be identified by a global address, as describedbelow. Table 1 illustrates an example of the source address (SA) and thedestination address (DA) at this point.

TABLE 1 SA 10.10.1.5 DA 10.10.1.27

At step 510, the packets received at NED 120 are translated from localaddresses for the address domain within access network 150 to globaladdresses. Not only can the destination address be translated into aglobal address, but the source address can also be translated into aglobal address. Table 2 illustrates a translation table for the callused at NED 120. Note that the global addresses used for the call can beassigned dynamically, for example, on a call-by-call basis so that whena call has ended, the global address can be reused for another,unrelated call.

TABLE 2 Local Address Global Address SA 10.10.1.5 135.4.1.7 DA10.10.1.27 135.4.2.15

At step 520, the packets are forwarded from the originating NED 120 tothe terminating NED 121. At this point, the packets have the globaladdress shown in Table 2.

At step 530, the packets received at the terminating NED 121 aretranslated from global addresses to addresses that are local to theaddress domain for which the terminating access network 151 is included.Table 3 illustrates a translation table for the call used at NED 121 fortranslating the global addresses to local addresses.

TABLE 3 Global Address Local Address 135.4.1.7 10.10.100.19 SA135.4.2.15 10.10.100.7 DA

At step 540, the packets translated by the terminating NED 121 are sentthrough access network 151 to the terminating TIU 171. Table 4illustrates the source address and the destination address for thepackets for the call as the packets are transmitted across terminatingaccess network 151, through terminating network interface unit 161 tothe terminating TIU 171.

TABLE 4 SA 10.10.100.19 DA 10.10.100.7

The translated packets are received at the terminating TIU 171 withoutrevealing the logical identity and the geographic identity of callingparty. Note that the called party only has access to the global sourceaddress and the global destination address which themselves aretranslations. Because the source address of calling party has beentranslated twice, once at the originating NED 120 and once at theterminating NED 121, address information about the calling party hasbeen altered beyond recognition to the calling party.

Once the call is completed, the translation tables at the originatingNED 120 and the terminating NED 121 can be deleted, and the globaladdresses can be released for reuse in another call. For example, if thenetwork address translation is incorporated into the funcitonality ofthe respective gates, the global addresses can be released when thegates are released. In another embodiment, the global addresses can bereleased after a time period of inactivity.

FIG. 5 illustrates the process by which packets are sent from theoriginating TIU 170 to the terminating TIU 171. Similarly, packets sentfrom the terminating TIU 171 to the originating TIU 170 can betranslated at the terminating NED 121 (reverse of the translation shownin Table 3) and again at the originating NED 120 (reverse of thetranslation shown in Table 2). Thus, the source address and thedestination address of the packets can be sent from the terminating TIU171 to the originating TIU 170 without revealing the logical identityand the geographic identity of called party.

The double translation of network addresses can be provided as a serviceto a subscriber by a service provider. In other words, a call can beconnected where the calling party and/or the called party subscribe tothe double translation service. FIG. 5 illustrates the case where theprivacy of both the calling party and the called party addressinformation is maintained: both the source address and the destinationaddress of packets for the call are translated as the packets are sentfrom the calling party to the called party and as packets for the callare sent from the called party to the calling party.

The double translation service can be provided to one party (i.e., onlythe calling party or the called party) without providing the service tothe other party. In such a case, for example where only the callingparty has subscribed to the double translation service, the first sourceaddress for packets sent from the originating TIU 170 are translated atthe originating NED 120 into a global source address, and the globaladdress for these packets are translated at the terminating NED 121 intoa second local source address. As packets are sent from the terminatingTIU 171, the second local source address is translated at theterminating NED 121 into the global source address, and the globalsource address is translated into the first source address at theoriginating NED 120.

In other words, where only one party has subscribed to the doubletranslation service, the address associated with that party istranslated twice. Consequently, the logical identity and the geographicidentity of that party is maintained in privacy from the other party forthe call.

The translation tables at the originating NED 120 and the terminatingNED 121 can be set up for a specific call and then can be deleted at theend of the call. This further ensures the privacy of the calling partyand/or called party because the global addresses are not repeated.Furthermore, by releasing the global addresses at the end of a call, theglobal addresses can be reused for another call having a differentcalling party and/or called party. Consequently, any potential shortagein the number of global addresses can be alleviated because the numberof active calls at one time is much less than the number of totalcalling parties and called parties.

6. Simulated Destination Ring Back

In another embodiment of the present invention, a ringback for a callbetween a calling party and a called party can be simulated. Aconnection acknowledgment associated with the call is received where thecalling party is located within a first network and the called party islocated within a second network. A prestored ring back signal from a setof prestored ringback signals is selected where the selected prestoredring back signal is associated with the second network. The selectedprestored ring back signal is sent to the calling party.

The prestored ringback signal can be, for example, a signal that isindicative of the network associated with the called party rather than asignal originated by that network. For example, a signal indicative of aforeign network (i.e., a network located in a foreign country) can bestored at a terminating TIU and provided within a ring back message sentto the origianting TIU. In such a case, the ring back signal cansimulate the ring back signal for that foreign country rather thanrelying on the actual foreign-network-originated ring back signal.

7. Protocol Description

This section contains details of the various protocols associated withembodiments of the present invention. This section is substantiallyidentical to the corresponding section of the parent U.S. Patentapplication, Ser. No. 09/366,207 filed Aug. 4, 1999 and allowed on Feb.11, 2002, which is hereby incorporated by reference. These include thecommunication between BTI and Gate Controller, between the BTI and EdgeRouter, between the BTI and other BTIs, between the Gate Controller andEdge Router, between Edge Router and Edge Router, and between GateController and Gate Controller.

All messages are given here in a text-based format, using a type/valuestructure. This is particularly easy for prototype implementations, andfor describing the interactions between network elements. However, ifany system components exist where memory is a serious limitation, it ispossible that a binary format could be used to conserve buffer spacerequirements.

A sample message is:

SETUP 0S55072 v1.0; DEST E164 8766; CALLER 8718 Bill Marshall; AUTHID3312120; CRV 21; CODING 53B,6 ms G.711

Messages consist of a sequence of type/value pairs. Each element of thesequence is separated by a semicolon; a semicolon at the end of themessage is optional. The type and value are ascii character strings,separated by white space (e.g. spaces or tabs). Generally every elementcontains at least two items, the type name and the parameter value, butmay contain several white-space separated parameter values.

The first element of every message is in a standard format. The type ofthe first element is the message name, the first parameter is thetransaction identifier, and the second parameter is the version number(v1.0 here).

Embodiments of the present invention can use an application-layerretransmission scheme to achieve reliable transport of messages. This isdone independent of any lower layer reliable transmission protocol,since the signaling system must also recover from component failures andrestart transactions when a component has failed. This often happensafter the component has received, acknowledged receipt, and has startedworking on a request; it is up to the application layer to realize thatno response is coming and to re-initiate the transaction.

We therefore specify the behavior of the network elements as if theunderlying transport is merely UDP/IP, and provides no buffering, flowcontrol, nor error recovery.

All basic message exchanges are transaction-based. All start with arequest message issued by a client, and sent to a server. The clientmust provide a unique transaction identifier for each separate request,and provide that transaction identifier in the standard place in allmessages. The client must insure that the transaction identifier is notreused for any subsequent messages for a period of at least somespecified interval. (approximately 30 seconds, exact value TBD).

A sample exchange begins with a client forming a request message andsending it to the server:

SETUP 1X64193 v1.0; <other stuff>

The message type is SETUP, the transaction identifier is 1X64193, andthe message is using version 1.0. When the server has completed the workrequested by this transaction, it sends one of two possible responses:

SETUPACK 1X64193 v1.0; <other stuff>or

SETUPNAK 1X64193 v1.0; <other stuff>.

The server must store all requests it receives for some period of time(30 seconds). The server must also store its responses for some periodof time (30 seconds) in case they were lost in transmission and need tobe resent.

If a client sends a request but does not receive a response within areasonable time (which may vary based on message type), it resends theoriginal request, without any modification.

If a server receives a request message that it recognizes as a duplicate(same source, same transaction identifier, same message type, notnecessary to compare message content), it either resends its response,if the response has been completed, or sends a pseudo-response:

WORKING 1X64193 v1.0;

The receipt of a WORKING message at the client indicates that the serverhas received the message, and the response has not yet been sent. It isreasonable for the client to use a longer timer before resending therequest again.

In some situations, e.g. the SETUP message, it is possible that thenormal processing time may exceed the timeout period of the client. Inthat case the server can immediately send the WORKING pseudo-responseupon receipt of a request.

Typical timeouts that seem reasonable to use are:

BTI to Edge Router: 0.5 seconds initially, 1 second after WORKINGresponse

BTI to Gate Controller: 1 second, 2 seconds after WORKING response

Gate Controller to GC: 1 second, 2 seconds after WORKING response

7.1 BTI to Gate Controller

The BTI initiates transactions with the Gate Controller to request a newconnection to a remote named endpoint, or to request some enhancedservice to be performed on an existing connection. In addition to basicconnections, this protocol enables all the custom calling features to beimplemented, and provides conference control capability.

This protocol is designed to utilize significant intelligence in theBTI, allowing it to completely handle the user interface and toimplement new custom services that build on the primitives that exist inthe signaling system of embodiments of the present invention.

Messages initiated by the BTI include SETUP, REDIRECT, SPLICE, TRACE,and PROFILE. SETUP is used to initiate a new connection. REDIRECT takesan existing connection and sends it to some other destination. SPLICEtakes two existing connections and connects them together. TRACEgenerates a law-enforcement report of an abusive or harassing call.PROFILE enables the BTI to specify custom call handling services fortimes when the BTI cannot be contacted (e.g. power failure).

7.1.1 SETUP

SETUP is the basic message sent by a BTI to initiate a connection toanother endpoint; an example message is:

SETUP 0S55072 v1.0; DEST E164 8766; CALLER 8718; AUTHID 3312120; CRV 21;SIGADDR wtm-bti:7685; DATAADDR wtm-bti:7000 2 2; CODING 53B,6 ms,G.711

DEST specifies the destination of this call. The first parameter in thisfield gives an address space name to search; valid address spaces areE164 (standard telephone numbers), CINFO (source string from a previouscall), and SERVICE (generic network service by name). The secondparameter gives the actual telephone number/source string/service name.Further parameters, if given, are passed through and given to thereceiving endpoint. Examples of various usages of the DEST element are:

DEST E164 8766 places a new call to a phone number. Second parameter isthe number in the customer's dialing plan (e.g. centrex, nanp, etc.)

DEST CINFO <string>places a return call to a previous caller, forexample, *69 return call. Second parameter is the string given in aSETUP, SETUPACK, or TRANSFER.

DEST SERVICE bridge 3 places a call to a network service, in thisexample a bridge service for 3 parties. The second parameter is the nameof the network service (e.g. bridge, announcement, etc.) and furtherparameters are given to that service for further interpretation.

CALLER gives the caller-id value for the line that is originating thiscall. The Gate Controller must verify that this caller-id is valid basedon the AUTHID. Since the BTI is outside out control, we cannot be surethat the call is really coming from the line it claims; however we canensure that the caller-id specified is one of the possible ones fromthis BTI.

AUTHID is the authorization code given to this particular BTI from theOAMP system. It is changed periodically, e.g. every ten minutes.

CRV is the Call Reference Value assigned for the BTI's end of this newcall. The CRV appears in all messages sent to the BTI, enabling the BTIto correctly assign the message to the proper call, and to properlyignore messages that refer to previous call attempts. Note that multiplerace conditions exist if a customer partially completes a call, hangsup, then places another call. The BTI needs some mechanism to ignorestale messages without the need to synchronize with all possible partiesprior to processing a new customer request (e.g. give the customeranother dialtone).

SIGADDR is the IP system name and port number that the called endpointshould use as a destination for all BTI-BTI messages. This may be thesame address and port as is used by the Gate Controller to signal anincoming call, or it may be a separate port for the current call only.If it is the same port, then it is necessary to structure the messagessuch that the BTI can distinguish GC-BTI messages from BTI-BTI messages,which this v1.0 design does.

DATAADDR is the IP system name and port specification that the calledendpoint should use as a destination for all voice data packets. Thefirst parameter is a system-name:port-number, where the port number isthe lowest port number in a set of consecutive ports. The secondparameter gives the size of the set of consecutive ports. The thirdparameter, if present, gives any alignment requirements of the portnumbers if it is necessary to translate them in a PAT server. A typicalvoice-only telephone call will use two ports, the first for RTP and thesecond for RTCP, and will require that the first port be even.

CODING specifies a list of possible encapsulations and coding methodsthat the originator will perform. Each parameter is at least three itemsseparated by commas, where the first item specifies a message size, thesecond item gives the interval between packets, the third item gives thecoding algorithm, and fourth and later items (optional) give additionalparameters specific to the coder.

7.1.1.1 SETUP Acknowledgment

The response to a SETUP message is SETUPACK or SETUPNAK. A sampleSETUPACK message is:

SETUPACK 0S55072 v1.0; CRV 3712;

SIGADDR 10.0.0.1:5134; DATAADDR 10.0.0.1:5136 2;

CODING 53B,6 ms,G.71 1; GATEIP 135.207.31.1:7682; GATEID 17S63224; CINFO<string>

CRV gives the Call Reference Value assigned by the remote endpoint toidentify all messages associated with the conversation. It must beincluded in all BTI-BTI messages.

SIGADDR gives the address and port to use as a destination for allBTI-BTI signaling messages.

DATAADDR gives the address and ports to use as a destination for allvoice data packets. The second parameter gives the number of consecutiveports allocated for this purpose.

CODING gives the single encapsulation and coding method, of the choicespresented in the SETUP message, that is acceptable to the destinationBTI. Format of the parameter is identical to that given above.

GATEIP gives the IP address and port number of the Edge Router thatcontains the gate controlling access service for this connection. Thisis the destination address to use for all BTI-ER messages.

GATEID gives the identification and authorization token assigned by theEdge Router for the gate allocated for this connection.

CINFO is an encrypted string of information from the Gate Controller,containing a number of items of state information needed by the GateController to properly handle any future requests for advanced featuresfor this call, e.g. 3-way calling, return call, transfer, etc. It mustbe stored unaltered by the BTI and returned to the Gate Controllerunaltered for any of these features.

7.1.1.2 SETUP Error

If the SETUP fails, the Gate Controller will return an error indicationto the BTI. A sample SETUPNAK message is:

SETUPNAK 0S55072 v1.0; ERROR Authorization failed

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so. Otherwise it provides some useful debugginginformation.

Other elements in the SETUPNAK message are TBD.

7.1.2 REDIRECT

The BTI sends a REDIRECT message to its Gate Controller when it wants acurrent call to be directed to some other destination. A sample REDIRECTmessage is:

REDIRECT 0S42115 v1.0; DEST E164 8720; CALLER 8766; AUTHID 6929022;

CINFO

135.207.31.2:7650/135.207.31.1:7682/17S63224/10.0.12.221:7685/10.0.12.221:7000-2-2/9733608718/21/10.0.12.221:7685

DEST gives the new desired destination of this call. It may be either anE164 number, a service name, or a CINFO string, just as in the SETUPmessage.

CALLER gives the caller-id value for the line that is making therequest. The Gate Controller must verify that this caller-id is validbased on the AUTHID. Since the BTI is outside our control, we cannot besure that the call is really coming from the line it claims; however wecan ensure that the caller-id specified is one of the possible ones fromthis BTI.

AUTHID is the authorization code given to this particular BTI from theOAMP system. It is changed periodically, e.g. every ten minutes.

CINFO is the encrypted string previously supplied by the GateController, which tells the Gate Controller various pieces ofinformation about the current call.

7.1.2.1 REDIRECT Acknowledgment

If the Gate Controller is successful in directing the call to the newdestination, it will respond with a REDIRECTACK message. A sample is:

REDIRECTACK 0S42115 v1.0;

7.1.2.2 REDIRECT Error

If the REDIRECT fails, the Gate Controller will return an errorindication to the BTI. A sample REDIRECTNAK message is:

REDIRECTNAK 0S55072 v1.0; ERROR Authorization failed

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so. Otherwise it provides some useful debugginginformation.

Other elements in the REDIRECTNAK message are TBD.

7.1.3 SPLICE

The BTI sends a SPLICE message to its Gate Controller when it wants twocurrent calls to be connected together. A sample SPLICE message is:

SPLICE 0S42161 v1.0; CALLER 8766; AUTHID 6929022;

CINFO1

135.207.31.2:7650/135.207.31.1:7682/17S63224/10.0.12.221:7685/10.0.12.221:7000-2-2/9733608718/21/10.0.12.221:7685;

CINF02

135.207.31.2:7650/135.207.22.1:7682/5S71731/10.3.7.150:7685/10.3.7.150:7000-2-2/9733608720/8839/10.3.7.150:7685

CALLER gives the caller-id value for the line that is making therequest. The Gate Controller must verify that this caller-id is validbased on the AUTHID. Since the BTI is outside our control, we cannot besure that the call is really coming from the line it claims; however wecan ensure that the caller-id specified is one of the possible ones fromthis BTI.

AUTHID is the authorization code given to this particular BTI from theOAMP system. It is changed periodically, e.g. every ten minutes.

CINFO1 is the encrypted string previously supplied by the GateController, which tells the Gate Controller various pieces ofinformation about the first call.

CINFO2 is the encrypted string previously supplied by the GateController, which tells the Gate Controller various pieces ofinformation about the second call.

7.1.3.1 SPLICE Acknowledgment

If the Gate Controller is successful in directing the two calls to eachother, it will respond with a SPLICEACK message. A sample is:

SPLICEACK 0S42161 v1.0;

7.1.3.2 SPLICE Error

If the SPLICE fails, the Gate Controller will return an error indicationto the BTI. A sample SPLICENAK message is:

SPLICENAK 0S55072 v1.0; ERROR Authorization failed

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so. Otherwise it provides some useful debugginginformation.

Other elements in the SPLICENAK message are TBD.

7.1.4 TRACE

The BTI sends a TRACE message to its Gate Controller when it to reportan abusive or harassing phone call to law enforcement. A sample TRACEmessage is:

TRACE 0S42115 v1.0; CALLER 8766; AUTHID 6929022;

CINFO

135.207.31.2:7650/135.207.31.1:7682/17S63224/10.0.12.221:7685/10.0.12.221:7000-2-2/9733608718/21/10.0.12.221:7685

CALLER gives the caller-id value for the line that is making therequest. The Gate Controller must verify that this caller-id is validbased on the AUTHID. Since the BTI is outside our control, we cannot besure that the call is really coming from the line it claims; however wecan ensure that the caller-id specified is one of the possible ones fromthis BTI.

AUTHID is the authorization code given to this particular BTI from theOAMP system. It is changed periodically, e.g. every ten minutes.

CINFO is the encrypted string previously supplied by the GateController, which tells the Gate Controller various pieces ofinformation about the call.

7.1.4.1 TRACE Acknowledgment

If the information in the TRACE message is valid, the Gate Controllerwill respond with a TRACEACK message. A sample message is:

TRACEACK 0S42115 v1.0;

7.1.4.2 TRACE Error

If the TRACE fails, the Gate Controller will return an error indicationto the BTI. A sample TRACENAK message is:

TRACENAK 0S55072 v1.0; ERROR Authorization failed

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so. Otherwise it provides some useful debugginginformation.

Other elements in the TRACENAK message are TBD.

7.1.5 PROFILE

To be provided.

7.1.5.1 PROFILE Acknowledgment

To be provided.

7.1.5.2 PROFILE Error

If the PROFILE fails, the Gate Controller will return an errorindication to the BTI. A sample PROFILENAK message is:

PROFILENAK 0S55072 v1.0; ERROR Authorization failed

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so. Otherwise it provides some useful debugginginformation.

Other elements in the PROFILENAK message are TBD.

7.2 Gate Controller to BTI

The Gate Controller initiates messages to the BTI to inform it ofincoming calls, or to inform it of a change in the status of an existingcall.

Messages initiated by the Gate Controller include SETUP, TRANSFER, andCALLHOLD. SETUP is used to inform the BTI of an incoming call, and toask the BTI the proper handling of this new call request. TRANSFERinforms the BTI that a current call has been redirected to a newdestination. CALLHOLD informs the BTI that the call has been placed onhold and to temporarily release the resources used by this call.

7.2.1 SETUP

The Gate Controller informs a BTI of an incoming call request with aSETUP message. A sample message is:

SETUP 4T93182 v1.0; DEST 9733608766; CALLER 9733608718; CRV 21; SIGADDR10.0.0.1:4722; DATAADDR 10.0.0.1:4724 2 2; CODING 53B,6 ms,G.7 11;GATEIP 135.207.22.1:7682; GATEID 21S11018; CINFO <string>

DEST is the destination E164 address, as given by the originator andexpanded to a global addressing plan by the Gate Controller.

CALLER (optional) is the caller-id information. This element is onlypresent if the customer has subscribed to some variant of caller-idservice. If the customer has subscribed to calling name service as well,the second parameter will contain the name of the caller. If theoriginator of the call has specified caller-id blocking, the firstparameter will contain “anonymous.”

CRV is the Call Reference Value assigned by the destination for thiscall. It must be included in all BTI-BTI messages to properly identifythe call.

SIGADDR gives the address and port number for the destination of allBTI-BTI signaling messages.

DATAADDR gives the address and port number for the destination of voicedata packets. The second parameter (optional) gives the number ofconsecutive ports allocated. The third parameter (optional) gives thealignment information for the port numbers.

CODING specifies a list of possible encapsulations and coding methodsthat the originator will perform. Each parameter is at least three itemsseparated by commas, where the first item specifies a message size, thesecond item gives the interval between packets, the third item gives thecoding algorithm, and fourth and later items (optional) give additionalparameters specific to the coder.

GATEIP gives the IP address and port number of the Edge Router thatcontains the gate controlling access service for this connection. Thisis the destination address to use for all BTI-ER messages.

GATEID gives the identification and authorization token assigned by theEdge Router for the gate allocated for this connection.

CINFO is an encrypted string containing internal state information ofthe Gate Controller, which is to be stored in the BTI and returned withany future enhanced service request related to this call, e.g. 3-waycalling, call transfer, etc.

7.2.1.1 SETUP Acknowledgment

If the BTI is willing to accept the incoming call specified in the SETUPmessage, it responds with SETUPACK. A sample SETUPACK message is:

SETUPACK 4T93182 v1.0; CRV 2712; SIGADDR kkrama-bti:7685; DATAADDRkkrama-bti:7000 2 2; CODING 53B,6 ms,G.711

CRV is the Call Reference Value assigned by the BTI for this call. It isthe value that will appear in all BTI-BTI messages to identify thespecific call instance.

SIGADDR is the address and port number where the BTI will listen forBTI-BTI signaling messages.

DATAADDR is the address and port numbers where the BTI will accept voicedata packets. The second parameter indicates the number of consecutiveports, and the third parameter gives the alignment necessary if the partnumbers are translated by a PAT server.

CODING is the encapsulation style and coding method chosen from thoseoffered.

7.2.1.2 SETUP Error

If the BTI is not willing to accept the incoming call, it responds withSETUPNAK. A sample SETUPNAK message is:

SETUPNAK 4T93182 v1.0; ERROR Busy; FORWARD E164 8800

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theoriginating BTI in a SETUPNAK message.

FORWARD gives the new destination that the call should be directed to,as a result of the call forwarding algorithm implemented within the BTI.The structure of this element is identical to that of the DEST elementof the BTI-GC SETUP message.

Other elements in the message are TBD.

7.2.2 TRANSFER

The TRANSFER messages is used by the Gate Controller to inform the BTIof a change in destination of an existing call. The BTI must alter somedestination parameters to communicate with this new destination. Asample TRANSFER message is:

TRANSFER OT5087 v1.0; CRV 21; REMCRV 1025; SIGADDR 135.207.31.3:6026;DATAADDR 135.207.31.3:6028 2; CODING 53B,6 ms,G.711; ROLE orig;

CINFO <string>

CRV gives the Call Reference Value of the call that has beentransferred. This parameter is intended to help the BTI determine theproper adjustments.

REMCRV is the Call Reference Value assigned by the party at the otherend of the call. This value must be used in all BTI-BTI communication.

SIGADDR is the IP address and port for BTI-BTI signaling messages to theother endpoint.

DATAADDR is the IP address and UDP port specification for voice datapackets. The second parameter, if present, gives the number ofconsecutive port numbers assigned for this connection. The thirdparameter, if present, tells any alignment necessary for the portnumbers.

CODING tells the encapsulation scheme and coding method to use for thisconnection.

ROLE tells whether the BTI should consider itself the originator orterminator of this conversation.

CINFO is an encrypted string of information about the other end of theconversation, to be stored in the BTI, for use for future enhancedservices that may be requested.

7.2.2.1 TRANSFER Acknowledgment

If the BTI is able to identify the call given in the TRANSFER message,adjust its internal state, and allocate resources to the newdestination, it responds with TRANSFERACK. A sample TRANSFERACK messageis:

TRANSFERACK 0T5087 v1.0;

7.2.2.2 TRANSFER Error

If the BTI is not willing to accept the transferred call, it respondswith TRANSFERNAK. A sample TRANSFERNAK message is:

TRANSFERNAK 0T5087 v1.0; ERROR Resource reservation to new destinationfailed

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theoriginating system in a NAK message.

Other elements in the message are TBD.

7.2.3 CALLHOLD

The BTI must be placed on hold while gate adjustments are performed. Inmost cases this is handled by the BTI-BTI HOLD message. In somesituations, it must be done by the Gate Controller, and is performed byissuing the CALLHOLD message. A sample CALLHOLD message is:

CALLHOLD 2T10477 v1.0; CRV 21

CRV is the Call Reference Value assigned by the BTI for thisconversation.

7.2.3.1 CALLHOLD Acknowledgment

After the BTI has placed itself in a hold status, it responds withCALLHOLDACK. A sample CALLHOLDACK message is:

CALLHOLDACK 2T10477 v1.0;

7.2.3.2 CALLHOLD Error

If the BTI is not able to process the HOLD request, it responds withCALLHOLDNAK. A sample CALLHOLDNAK message is:

CALLHOLDNAK 2T10477 v1.0; ERROR Illegal Call Reference Value ERROR givesan error message string, which could be displayed if the Gate Controllerhas some method to do so, and can be passed back to the originatingsystem in a NAK message.

7.3 BTI to Edge Router

Resource allocation messages are exchanged between the BTI and the EdgeRouter for reservation and release of network resources. These messagesall have a reference to a “Gate,” which must have been initialized by aGate Controller prior to the BTI's resource reservation request.

Messages initiated by the BTI include RESERVE, COMMIT, RERESERVE,RECOMMIT, RELEASE, HOLD, and KEEPALIVE. RESERVE is the normal first stepin the reservation protocol, where it requests an allocation ofresources but does not require them to be assigned. COMMIT requests theactual assignment of resources to this conversation. RERESERVE is usedin cases where the BTI already has some resources either reserved orcommitted to it and is willing to use them to satisfy this new request.RECOMMIT serves a similar function when the resources are to becommitted to this new connection. RELEASE is the indication from the BTIthat a connection should be terminated. HOLD indicates to the EdgeRouter that the voice data stream is temporarily stopping, and to stopmonitoring the data stream, but to maintain the resources as reserved.KEEPALIVE is sent periodically (interval TBD) in the held state to theEdge Router to maintain the resource reservation; a lack of keepalivesindicates a (probably undesirable) call termination.

7.3.1 RESERVE

The RESERVE message is sent by the BTI in the first stage of resourceallocation. A sample RESERVE message is:

RESERVE 0S55073 v1.0; GATEID 17S63224; BANDWIDTH 53B,6 ms

GATEID is the identification of the gate, as assigned by the EdgeRouter. Included in this string is the security authorization thatindicates the sender is allowed to perform operations on this gate.

BANDWIDTH is the specification of the actual bandwidth desired at thistime. It is specified as packet size, in bytes, and inter-packetinterval. The details of the algorithm for comparing this to thespecification given by the Gate Controller in the GATESETUP message isTBD.

7.3.1.1 RESERVE Acknowledgment

If the resource reservation is successful, meaning bandwidth isavailable both upstream and downstream in the access network, andbandwidth is available in the forward direction in the backbone network,the Edge Router responds with a RESERVACK message. A sample message is:

RESERVEACK 0S55073 v1.0;

7.3.1.2 RESERVE Error

If the resource reservation fails, the Edge Router responds with aRESERVENAK message. A sample message is:

RESERVENAK 0S55073 v1.0; ERROR No upstream capacity available ERRORgives an error message string, which could be displayed if the BTI hassome method to do so, or can simply result in a fast busy signal.

Other elements in the message are TBD.

7.3.2 COMMIT

The COMMIT message is sent by the BTI in the second stage of resourceallocation. On receipt of a COMMIT message, the Edge Router resets thegate timer to a smaller interval (approximately 2 seconds, exact valueTBD). If that timer expires before the COMMITACK is sent, the gate isterminated. A sample COMMIT message is:

COMMIT 0S55074 v1.0; GATEID 17S63224; BANDWIDTH 53B,6 ms

GATEID is the identification of the gate, as assigned by the EdgeRouter. Included in this string is the security authorization thatindicates the sender is allowed to perform operations on this gate.

BANDWIDTH is the specification of the actual bandwidth desired at thistime. It is specified as packet size, in bytes, and inter-packetinterval. The details of the algorithm for comparing this to thespecification given by the Gate Controller in the GATESETUP message isTBD. The value given in the COMMIT can be no greater than that from theRESERVE message; again the comparison method is TBD.

7.3.2.1 COMMIT Acknowledgment

If the resource allocation is successful, meaning bandwidth has beenallocated in the access network (e.g. via unsolicited grants), and theEdge Router has successfully coordinated with its remote Edge Router atthe other end of the call, the Edge Router responds with a COMMITACKmessage. A sample message is:

COMMITACK 0S55074 v1.0;

7.3.2.2 COMMIT Error

If the resource allocation fails, or the coordination with the remotegate does not complete within the allotted interval, the Edge Routerresponds with a COMMITNAK message. It is intended that this be a veryinfrequent event, since it results in the caller hearing first aringback tone, then turning into a failure tone. Such call defects arelimited by the service description to only a few per million completedcalls, although deliberate cases of fraud causing this error are notcounted. A sample message is:

COMMITNAK 0S55074 v1.0; ERROR Gate coordination failure

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so, or can simply result in a fast busy signal.

Other elements in the message are TBD.

7.3.3 RERESERVE

The RERESERVE message is sent by the BTI in the first stage of resourceallocation when the BTI has a current allocation that the new connectionwill be re-using. See Section xx.xx for information about the two stageresource allocation scheme. A sample RERESERVE message is:

RERESERVE 0S42110 v1.0; GATEID 5S71731; PREVGATEID 21S11018; BANDWIDTH53B,6 ms

GATEID is the identification of the gate, as assigned by the EdgeRouter. Included in this string is the security authorization thatindicates the sender is allowed to perform operations on this gate.

PREVGATEID is the identification of an existing, committed gate, whoseresources will be re-used in the current connection.

BANDWIDTH is the specification of the actual bandwidth desired at thistime. It is specified as packet size, in bytes, and inter-packetinterval. The details of the algorithm for comparing this to thespecification given by the Gate Controller in the GATESETUP message isTBD.

7.3.3.1 RERESERVE Acknowledgment

If the resource re-reservation is successful, meaning bandwidth isavailable both upstream and downstream in the access network, andbandwidth is available in the forward direction in the backbone network,the Edge Router responds with a RERESERVACK message. A sample messageis:

RESERVEACK 0S42110 v1.0;

7.3.3.2 RERESERVE Error

If the resource re-reservation fails, the Edge Router responds with aRERESERVENAK message. A sample message is:

RERESERVENAK 0S42110 v1.0; ERROR Illegal previous gate identifier

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so, or can simply result in a fast busy signal.

Other elements in the message are TBD.

7.3.4 RECOMMIT

The RECOMMIT message is sent by the BTI in the second stage of resourceallocation when a previous allocation is to be re-used. See Sectionxx.xx for information about the two stage resource allocation scheme. Onreceipt of a RECOMMIT message, the Edge Router resets the gate timer toa smaller interval (approximately 2 seconds, exact value TBD). If thattimer expires before the RECOMMITACK is sent, the gate is terminated. Asample RECOMMIT message is:

RECOMMIT 0S42111 v1.0; GATEID 5S71731; PREVGATEID 21S11018; BANDWIDTH53B,6 ms

GATEID is the identification of the gate, as assigned by the EdgeRouter. Included in this string is the security authorization thatindicates the sender is allowed to perform operations on this gate.

PREVGATEID is the identification of an existing, committed gate, whoseresources may be re-used in the current connection.

BANDWIDTH is the specification of the actual bandwidth desired at thistime. It is specified as packet size, in bytes, and inter-packetinterval. The details of the algorithm for comparing this to thespecification given by the Gate Controller in the GATESETUP message isTBD. The value given in the COMMIT can be no greater than that from theRESERVE message; again the comparison method is TBD.

7.3.4.1 RECOMMIT Acknowledgment

If the resource allocation is successful, meaning bandwidth has beenallocated in the access network (e.g. via unsolicited grants), and theEdge Router has successfully coordinated with its remote Edge Router atthe other end of the call, the Edge Router responds with a RECOMMITACKmessage. A sample message is:

RECOMMITACK 0S42111 v1.0;

7.3.4.2 RECOMMIT Error

If the resource allocation fails, or the coordination with the remotegate does not complete within the allotted interval, the Edge Routerresponds with a RECOMMITNAK message. It is intended that this be a veryinfrequent event, since it results in the caller hearing first aringback tone, then turning into a failure tone. Such call defects arelimited by the service description to only a few per million completedcalls, although deliberate cases of fraud causing this error are notcounted. A sample message is:

RECOMMITNAK 0S42111 v1.0; ERROR Gate coordination failure

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so, or can simply result in a fast busy signal.

Other elements in the message are TBD.

7.3.5 RELEASE

The BTI sends the RELEASE message to the Edge Router when the call hascompleted, and the resources are to be released and billing is to stop.A sample message is:

RELEASE 0S55075 v1.0; GATEID 17S63224

GATEID is the identification of the gate that was assigned for thisconversation, and which is now to be released.

7.3.5.1 RELEASE Acknowledgment

The Edge Router always responds to a RELEASE message with RELEASEACK. Ifa gate existed with the indicated identification, then it is closed, itsresources released, a billing event is generated, and a GATECLOSEmessage is sent to the corresponding Edge Router at the other end of theconnection.

A sample message is:

RELEASEACK 0S55075 v1.0;

7.3.5.2 RELEASE Error

The Edge Router always responds to a RELEASE with a RELEASEACK. Thereare no error indications generated. If the gate identification does notexist, the Edge Router assumes the gate has already been closed by theremote end.

7.3.6 HOLD

If the BTI wants to place a current call on hold, it must inform theEdge Router that its upstream data stream will stop. Otherwise, the EdgeRouter will interpret the lack of data as a hangup indication andterminate the call. This is done by a HOLD message. A sample message is:

HOLD 0S55090 v1.0; GATEID 17S63224

GATEID is the identification of the gate, as assigned by the EdgeRouter. Included in this string is the security authorization thatindicates the sender is allowed to perform operations on this gate.

7.3.6.1 HOLD Acknowledgment

If the hold operation is successful, meaning bandwidth has been placedback in the pool of reserved but not yet committed, the Edge Routerresponds with a HOLDACK message. A sample message is:

HOLDACK 0S55090 v1.0;

7.3.6.2 HOLD Error

If the hold operation fails the Edge Router responds with a HOLDNAKmessage. A sample message is:

HOLDNAK 0S55090 v1.0; ERROR Gate not yet committed

ERROR gives an error message string, which could be displayed if the BTIhas some method to do so, or can simply result in a fast busy signal.

Other elements in the message are TBD.

7.3.7 KEEPALIVE

While having a connection on hold, it is necessary for the BTI toperiodically inform the Edge Router that it is still alive and healthy,and that the reservation should be maintained. Lack of any traffic fromthe BTI is taken as evidence that the BTI has failed, or that someaccess component has failed and that the BTI is unable to request a calltermination. The safe strategy is to terminate the call, rather thanpossibly charge the customer for a length service outage. A sampleKEEPALIVE message is:

KEEPALIVE 21C3972 v1.0; GATEID 17S63224

GATEID is the identification of the gate, as assigned by the EdgeRouter. Included in this string is the security authorization thatindicates the sender is allowed to perform operations on this gate.

There is no error control or retransmission of KEEPALIVE messages. Theinterval between them is engineered to minimize the chances of falseerror detection.

7.4 Edge Router to BTI

No messages are initiated by the Edge Router.

7.5 BTI to BTI

There are various end-to-end messages that are exchanged in anysignaling system, which are used to coordinate the state of the twoendpoints in providing consistent service. In embodiments of the presentinvention these are implemented as BTI-BTI signaling messages, are sentdirectly between the two BTIs involved in the conversation. These areformatted such that they can be processed by the same subroutines as theother messages. Messages exchanged between BTIs include RING, RINGBACK,CONNECT, HANGUP, HOLD, and RINGTIMEOUT. RING is sent from the originatorto the destination to indicate that all appears ready and that thedestination should ring the phone. RINGBACK is sent from the destinationto the originator to indicate that the phone is ringing. CONNECT is sentfrom the destination to the originator when the called party answers thephone, or immediately after receipt of RING is the called party isready. HOLD is sent from either BTI to the other to indicate the callwill be placed on hold and to release any real-time resources currentlyheld. HANGUP and RINGTIMEOUT are informational messages to indicatestate information that the BTI will receive by other mechanisms as well.

7.5.1 RING

The RING message is sent by the originating BTI when it has received theacknowledgment from its Edge Router that resources are available for thecall, and therefore it is time to alert the destination user. A samplemessage is:

RING 3712 v1.0; CRV 3712

CRV (optional) is the Call Reference Value assigned by the destinationBTI. It must appear in the message, but may appear either as thetransaction identifier, or as a separate element.

The acknowledgment of RING is either RINGBACK or CONNECT, not a separateRINGACK message.

7.5.2 RINGBACK

When a terminating BTI has completed the resource reservation sequence,and has received a RING message from the originating BTI, its properresponse is either RINGBACK or CONNECT. RINGBACK is sent if thedestination is not yet ready to receive the call, and that the BTI isringing the phone. CONNECT means the destination is ready now, and thatno ringing is needed (e.g. a voice response system). A sample messageis:

RINGBACK 21 v1.0; CRV 21; SOURCE local; TYPE callwaiting

CRV (optional) is the Call Reference Value assigned by the originatingBTI. It must appear in the message, but may appear either as thetransaction identifier, or as a separate element.

SOURCE (optional) specifies whether the audible ringback tone is to begenerated locally by the originating BTI, or whether the destinationwill generate the tone utilizing the data stream. Due to the resourcereservation scheme, SOURCE specified as “remote” can only occur when thedestination is a trusted network element that does not need a gate tocontrol access to the network. If not specified, ringback tone isgenerated locally by the BTI.

TYPE (optional) specifies one of several possible ringback audiosequences. Parameter value “callwaiting” means the special tone sequenceindicating the callwaiting alert signal has been given. If the parameteris not given, or not understood, it defaults to “normal”.

There is no explicit acknowledgment to RINGBACK. However, if theoriginating BTI does not receive either RINGBACK or CONNECT in responseto its RING message, it will retransmit the RING until a response isreceived.

7.5.3 CONNECT

The CONNECT message is sent by the terminating BTI when the user hasanswered and the connection should be established. A sample message is:

CONNECT 21 v1.0; CRV 21

CRV (optional) is the Call Reference Value assigned by the originatingBTI. It must appear in the message, but may appear either as thetransaction identifier, or as a separate element.

Acknowledgment of the CONNECT message occurs via the COMMIT/COMMITACKexchange with the Edge Router.

7.5.4 HANGUP

This is an information message that is sent by either BTI to the otherone to indicate the user is terminating the connection. A sample messageis:

HANGUP 3712 v1.0; CRV 3712

CRV (optional) is the Call Reference Value assigned by the originatingBTI. It must appear in the message, but may appear either as thetransaction identifier, or as a separate element.

There is no acknowledgment of the HANGUP message. There are multipleindependent mechanisms that determine that a call has completed and willterminate the billing; since the system must recover from access linkfailures, BTI hardware/software failures, and power failures, each ofwhich may prevent the BTI from sending the HANGUP message. Therefore itsuse is not critical.

7.5.5 HOLD

If the BTI wants to place a current call on hold, it must inform theother endpoint that its incoming data stream will stop. Otherwise, theother endpoint will interpret the lack of data as a hangup indicationand terminate the call. This is done by a HOLD message. A sample messageis:

HOLD 21 v1.0; CRV 21

CRV (optional) is the Call Reference Value assigned by the originatingBTI. It must appear in the message, but may appear either as thetransaction identifier, or as a separate element.

Note that before stopping the data stream, the BTI must also inform itsEdge Router that the data stream will stop, else the Edge Router willterminate the call. This is done via a BTI-ER HOLD message.

7.5.5.1 HOLD Acknowledgment

When a BTI has received a HOLD message from the other endpoint, itadjusts its threshold for considering the connection dead, and respondswith the acknowledgment. This message is:

HOLDACK 3712 v1.0; CRV 3712

CRV (optional) is the Call Reference Value assigned by the originatingBTI. It must appear in the message, but may appear either as thetransaction identifier, or as a separate element.

7.5.6 RING TIMEOUT

This is an information message that is sent by the terminating BTI tothe originator to indicate the user has not answered within the intervalthey configured, and that the call will be forwarded. A sample messageis:

RINGTIMEOUT 3712 v1.0; CRV 3712

CRV (optional) is the Call Reference Value assigned by the originatingBTI. It must appear in the message, but may appear either as thetransaction identifier, or as a separate element.

There is no error recovery for this message. It is informational only,and serves to tell the originating BTI to stop the ringback tone, andthat a transfer is imminent. Without this message the originating BTIwill still receive a TRANSFER message from the Gate Controller andhandle the call in the same way.

7.5.7 RESOURCECHANGE

TBD

7.5.8 KEEPALIVE

While having a connection on hold, it is necessary for the BTI toperiodically inform its peer BTI that it is still alive and healthy, andthat the connection should be maintained. Lack of any traffic from theBTI is taken as evidence that the BTI has failed, or that some accesscomponent has failed and that the BTI is unable to request a calltermination. The safe strategy is to terminate the call, rather thanpossibly charge the customer for a length service outage. A sampleKEEPALIVE message is:

KEEPALIVE 3712 v1.0; CRV 3712

CRV (optional) is the Call Reference Value assigned by the other BTI. Itmust appear in the message, but may appear either as the transactionidentifier, or as a separate element.

There is no error control or retransmission of KEEPALIVE messages. Theinterval between them is engineered to minimize the chances of falseerror detection.

7.6 Gate Controller to Edge Router

The protocol between the Gate Controller and Edge Router is for purposesof resource control and resource allocation policy. The Gate Controllerimplements all the allocation policies, and uses that information tomanage the set of gates implemented in the Edge Routers. The GateController initializes the gates with specific source, destination, andbandwidth restrictions; once initialized the BTI is able to requestresource allocations within the limits imposed by the Gate Controller.

Messages initiated by the Gate Controller include GATEALLOC, GATESETUP,GATEMODIFY, GATERELEASE, and GATEINFO. GATEALLOC allocates a new gateidentifier. GATESETUP initializes all the policy and traffic parametersfor the gate, and sets the billing information. GATEMODIFY is used tochange any or all of the parameters of an existing gate. GATERELEASEsignals the end of the connection, and that the gate and all itsresources can be made available to any other requester. GATEINFO is amechanism by which the Gate Controller can find out all the currentstate and parameter settings of an existing gate.

7.6.1 GATEALLOC

A GATEALLOC message is sent by the Gate Controller to allocate a newgate, and establish a GateID, but without setting any of the specificparameters needed for gate operation. A GATESETUP must come later withthe operation parameters. On receipt of a GATEALLOC, the Edge Routerstarts a timer (approximately 120 seconds, exact value TBD), and if thegate has not entered the “commit” state in that time it is released. Asample GATEALLOC message is:

GATEALLOC 4T93176 v1.0; OWNER wtm-bti:7685

OWNER specifies the name of the customer this gate will serve.

7.6.1.1 GATEALLOC Acknowledgment

A sample GATEALLOC message is:

GATEALLOCACK4T93176 v1.0; GATEID 17S63224; CUSTUSAGE 3

GATEID is the string that identifies the gate that was allocated. Itconsists of at least two parts, with some (edge-router-specified)separator between them: the identity of the gate that was allocated, anda security code that must be given to the Edge Router in order to affectany change in the gate parameters.

CUSTUSAGE tells the Gate Controller the number of simultaneous gates thecustomer has currently. This is calculated by a scan of all currentgates, comparing the OWNER parameter. If the number of gates assigned toa customer is inconsistent with the service subscribed, the GateController can take appropriate action.

7.6.1.2 GATEALLOC Error

Errors in allocating gates are reported by a GATEALLOCNAK message. Asample is:

GATEALLOCNAK 4T93176 v1.0; ERROR No gates available

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a SETUPNAK message.

Other elements in the message are TBD.

7.6.2 GATESETUP

The GATESETUP message is sent by the Gate Controller to the Edge Routerto initialize the operational parameters of the gate. A sample GATESETUPmessage is:

GATESETUP 4T93181 v1.0; OWNER kkrama-bti:7685;

SRCIP 10.3.7.151; DESTIP 10.0.0.1:4724; BANDWIDTH 53B,6 ms,G.711;

ROLE term; REMGATEIP 135.207.31.1:7682; REMGATEID 17S63224;

REFID 135.207.31.2:36123E5C:93178;

BILLDATA 5123-0123-4567-8900/9733608718/9733608766

OWNER (optional) gives the name of the customer this gate will serve. Ifthis parameter is not given, then GATEID is mandatory.

GATEID (optional) gives the string that identifies the gate, withsecurity code. If this parameter is not given, then OWNER is mandatory,and a new gate will be allocated.

SRCIP identifies the source IP address that will appear in all the datapackets that go through the gate. Note that the source port number isnot specified, and is generally not known or always constant.

DESTIP is the destination IP address that will appear in the IP header,and the destination UDP port number that will appear in the UDP header.Only packets that match the SourceIP/DestinationIP/DestinationPort willobtain the higher Quality of Service provided by the gate.

BANDWIDTH specifies the maximum bandwidth that maybe requested throughthis gate. Although the parameter includes the coding style, it is notused by the gate.

ROLE specifies whether the Edge Router is the originator or terminatingside of this conversation. This has importance only if the backbonereservation is bi-directional, and only one of the Edge Routers need dothe reservation.

REMGATEIP is the address of the Edge Router at the other end of thisconnection. All ER-ER gate coordination messages are to be sent to thisaddress and port.

REMGATEID is the identity of the gate at the other end of theconnection.

REFID is the unique string that is to appear in billing records for thisconversation.

BILLDATA is the charging information that is to appear in billingrecords for this conversation.

7.6.2.1 GATESETUP Acknowledgment

A sample GATESETUPACK message is:

GATESETUPACK4T93181 v1.0; GATEID 21S11018; CUSTUSAGE 1

GATEID is the string that identifies the gate that was allocated. Itconsists of at least two parts, with some (edge-router-specified)separator between them: the identity of the gate that was allocated, anda security code that must be given to the Edge Router in order to affectany change in the gate parameters.

CUSTUSAGE tells the Gate Controller the number of simultaneous gates thecustomer has currently. This is calculated by a scan of all currentgates, comparing the OWNER parameter. If the number of gates assigned toa customer is inconsistent with the service subscribed, the GateController can take appropriate action.

7.6.2.2 GATESETUP Error

Errors in establishing gates are reported by a GATESETUPNAK message. Asample is:

GATESETUPNAK 4T93181 v1.0; ERROR No gates available

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a SETUPNAK message.

Other elements in the message are TBD.

7.6.3 GATEMODIFY

The GATEMODIFY message is sent by the Gate Controller to the Edge Routerto modify the operational parameters of an existing gate. A sampleGATEMODIFY message is:

GATEMODIFY 2T10486 v1.0; GATEID 17S63224; SRCIP 10.3.7.151; DESTIP10.0.0.1:4724; BANDWIDTH 53B,6 ms,G.711; ROLE term; REMGATEIP135.207.31.1:7682; REMGATEID 17S63224; REFID135.207.31.2:36123E5C:93178; BILLDATA5123-0123-4567-8900/9733608718/9733608766q

GATEID gives the string that identifies the gate, with security code.

SRCIP identifies the source IP address that will appear in all the datapackets that go through the gate. Note that the source port number isnot specified, and is generally not known or always constant.

DESTIP is the destination IP address that will appear in the IP header,and the destination UDP port number that will appear in the UDP header.Only packets that match the SourceIP/DestinationIP/DestinationPort willobtain the higher Quality of Service provided by the gate.

BANDWIDTH specifies the maximum bandwidth that may be requested throughthis gate. Although the parameter includes the coding style, it is notused by the gate.

ROLE specifies whether the Edge Router is the originator or terminatingside of this conversation. This has importance only if the backbonereservation is bi-directional, and only one of the Edge Routers need dothe reservation.

REMGATEIP is the address of the Edge Router at the other end of thisconnection. All ER-ER gate coordination messages are to be sent to thisaddress and port.

REMGATEID is the identity of the gate at the other end of theconnection.

REFID is the unique string that is to appear in billing records for thisconversation.

BILLDATA is the charging information that is to appear in billingrecords for this conversation.

7.6.3.1 GATEMODIFY Acknowledgment

A sample GATEMODIFYACK message is:

GATEMODIFYACK 2T10486 v1.0; GATEID 17S63224; CUSTUSAGE 1

GATEID is the string that identifies the gate that was allocated. Itconsists of at least two parts, with some (edge-router-specified)separator between them: the identity of the gate that was allocated, anda security code that must be given to the Edge Router in order to affectany change in the gate parameters.

CUSTUSAGE tells the Gate Controller the number of simultaneous gates thecustomer has currently. This is calculated by a scan of all currentgates, comparing the OWNER parameter. If the number of gates assigned toa customer is inconsistent with the service subscribed, the GateController can take appropriate action.

7.6.3.2 GATEMODIFY Error

Errors in modifying gates are reported by a GATEMODIFYNAK message. Asample is:

GATEMODIFYNAK 4T93181 v1.0; ERROR Illegal Gate Identification

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a SETUPNAK message.

Other elements in the message are TBD. 7.6.4 GATERELEASE

When a Gate Controller has transferred a connection, it sends aGATERELEASE message to the Edge Router to release any resources held bythe endpoint that is now not part of the call. While the behavior issimilar to a RELEASE message from the BTI, it results in a differentevent recorded in the billing system, and it avoids the normal gatecoordination (as the corresponding gate at the other end of the originalconnection has been redirected to another destination). A sample is:

GATERELEASE 4T93181 v1.0; GATEID 17S63224

GATEID is the string that identifies the gate that was allocated. Itconsists of at least two parts, with some (edge-router-specified)separator between them: the identity of the gate that was allocated, anda security code that must be given to the Edge Router in order to affectany change in the gate parameters.

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a SETUPNAK message. Other elements in the message are TBD.

7.6.4.1 GATERELEASE Acknowledgment

A GATERELEASE message always gives a response of GATERELEASEACK. Asample is:

GATERELEASEACK 4T93181 v1.0;

7.6.4.2 GATERELEASE Error

A GATERELEASE message always results in a response of GATERELEASEACK. Ifthe GATEID parameter specifies an invalid gate, the Edge Router assumesthe gate has already been closed.

7.6.5 GATEINFO

When a Gate Controller wishes to find out the current parametersettings, or current state, of a gate, it sends to the Edge Router aGATEINFO message. A sample is:

GATEINFO OT5082 v1.0; GATEID 17S63224

GATEID is the string that identifies the gate that was allocated. Itconsists of at least two parts, with some (edge-router-specified)separator between them: the identity of the gate that was allocated, anda security code that must be given to the Edge Router in order to affectany change in the gate parameters.

7.6.5.1 GATEINFO Acknowledgment

The message is sent by the Gate Controller to the Edge Router to modifythe operational parameters of an existing gate. A sample GATEINFOACKmessage is:

GATEINFOACK OT5082 v1.0; GATEID 17S63224; STATE commit; SRCIP10.3.7.151; DESTIP 10.0.0.1:4724; BANDWIDTH 53B,6 ms,G.711;

ROLE term; REMGATEIP 135.207.31.1:7682; REMGATEID 17S63224;

REFID 135.207.31.2:36123E5C:93178;

BILLDATA 5123-0123-4567-8900/9733608718/9733608766

GATEID gives the string that identifies the gate, with security code.

STATE gives the internal state of the gate, one of the following: setup,reserved, commit, or hold.

SRCIP identifies the source IP address that will appear in all the datapackets that go through the gate. Note that the source port number isnot specified, and is generally not known or always constant.

DESTIP is the destination IP address that will appear in the IP header,and the destination UDP port number that will appear in the UDP header.Only packets that match the SourceIP/DestinationIP/DestinationPort willobtain the higher Quality of Service provided by the gate.

BANDWIDTH specifies the maximum bandwidth that maybe requested throughthis gate. Although the parameter includes the coding style, it is notused by the gate.

ROLE specifies whether the Edge Router is the originator or terminatingside of this conversation. This has importance only if the backbonereservation is bi-directional, and only one of the Edge Routers need dothe reservation.

REMGATEIP is the address of the Edge Router at the other end of thisconnection. All ER-ER gate coordination messages are to be sent to thisaddress and port.

REMGATEID is the identity of the gate at the other end of theconnection.

REFID is the unique string that is to appear in billing records for thisconversation.

BILLDATA is the charging information that is to appear in billingrecords for this conversation.

7.6.5.2 GATEINFO Error

Errors in fetching gate information are reported by a GATEINFONAKmessage. A sample is:

GATEINFONAK 0T5082 v1.0; ERROR Illegal Gate Identification

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a SETUPNAK message.

Other elements in the message are TBD.

7.7 Edge Router to Gate Controller

No messages are initiated by the Edge Router.

7.8 Edge Router to Edge Router

In order to prevent some types of theft of service fraud, it isnecessary for the Edge Routers to synchronize the gates at opposite endsof a connection. In particular, a gate that is “committed” at one end ofa connection, but not at the other, can be used as a high quality dataconnection, or can be used to fraudulently charge an unsuspectingcustomer for a lengthy connection.

Messages exchanged between the Edge Routers include GATEOPEN, andGATECLOSE. GATEOPEN is exchanged with the gate has resources committedto it, and GATECLOSE is exchanged when those resources are released.Timers within the gate implementation impose strict controls on thelength of time these exchanges may occupy.

7.8.1 GATEOPEN

The GATEOPEN message is sent by the Edge Router to its correspondingEdge Router at the other end of a connection on receipt of the COMMITmessage from the BTI. A sample message is:

GATEOPEN 21T6572; GATEID 17S63224; BANDWIDTH 53B,6 ms

GATEID is the identification string for the remote gate, including thesecurity code required.

BANDWIDTH is the bandwidth request received in the COMMIT message.

7.8.1.1 GATEOPEN Acknowledgment

On receipt of a GATEOPEN message, the Edge Router responds with aGATEOPENACK. A sample message is:

GATEOPENACK 21T6572 v1.0;

7.8.1.2 GATEOPEN Error

If some error occurs in the processing of a GATEOPEN, the Edge Routerresponds with GATEOPENNAK. Such a situation can occur when the remotegate times out and releases the gate before the commit sequencecompletes. A sample message is:

GATEOPENNAK 21T6572 v1.0; ERROR Invalid gate identifier

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a SETUPNAK message.

Other elements in the message are TBD.

7.8.2 GATECLOSE

The GATECLOSE message is sent by the Edge Router to its correspondingEdge Router at the other end of a connection on receipt of the RELEASEmessage from the BTI. The Edge Router releases any resources held bythat gate, stops any unsolicited grants offered on the upstream channel,and frees the gate. A sample message is:

GATECLOSE 21T6583; GATEID 17S63224;

GATEID is the identification string for the remote gate, including thesecurity code required.

7.8.2.1 GATECLOSE Acknowledgment

On receipt of a GATECLOSE message, the Edge Router responds with aGATECLOSEACK. A sample message is: GATECLOSEACK 21T6583 v1.0;

7.8.2.2 GATECLOSE Error

A GATECLOSE message always results in a response of GATECLOSEACK. If theGATEID parameter specifies an invalid gate, the Edge Router assumes thegate has already been closed.

7.9 Gate Controller to Gate Controller

Messages exchanged between the Gate Controllers include GCSETUP,GCREDIRECT, and GCSPLICE. All occur in situations where the GateController realizes that it cannot complete a request due to thedestination being served by a different Gate Controller. These messagespackage up all the internal state, ask the remote Gate Controller tocomplete the desired function, then respond with the updated stateinformation. In an implementation of the Gate Controller it is likelythat these messages will exist in some internal form in order to sharethe implementation of call termination services.

7.9.1 GCSETUP

The GCSETUP message is exchanged between Gate Controllers when differentGate Controllers serve the originating and terminating endpoints of acall. It is basically formed by packaging all the partial stateinformation the originating Gate Controller has assembled, andrequesting the terminating Gate Controller to complete the worknecessary to initiate the connection.

A sample GCSETUP message is:

GCSETUP 4T93177 v1.0; DEST E164 9733608766; CALLER 9733608718 BillMarshall;

CRV 21; SIGADDR 135.207.31.1:6000; DATAADDR 135.207.31.1:6002 2 2;REMGATEIP 135.207.31.1:7682; REMGATEID 17S63224;

CODING 53B,6 ms,G.71 1; REFID 135.207.31.2:36123E5C:93178; BILLDATA5123-0123-4567-8900/9733608718/9733608766;

CINFO

135.207.31.2:7650/135.207.31.1:7682/17S63224/10.0.12.221:7685/10.0.12.221:7000-2-2/9733608718/21/10.0.12.221:7685

DEST is the destination address for this connection. Its format is thesame as in the SETUP message received from the BTI, except that the E164number, if present, is expanded from the local numbering plan of thecustomer to the global numbering plan.

CALLER is the caller-id and calling name of the originator of theconnection. From the SETUP message received from the BTI, theoriginating Gate Controller expanded the E 164 number to a globalnumbering plan, and looked up the calling name.

CRV is the Call Reference Value assigned by the originating BTI. Copiedfrom the SETUP message.

SIGADDR is the IP address and port number the destination should use forBTI-BTI signaling messages. This is a global version of the addressgiven in the SETUP message from the BTI, with name to ip-addresstranslation done, and with any NAT/PAT server translation included.

DATAADDR is the IP address and port number the destination should usefor data packets. This is a global version of the address given in theSETUP message from the BTI, with name and ip-address translation done,and with any NAT/PAT server translation included. The second and thirdparameters (optional) in this element give the number of consecutiveports used, and the alignment information needed for the starting portnumber.

REMGATEIP is the IP address and port number of the Edge Router thatcontains the gate to be used for this conversation. This is thedestination address for all ER-ER communication.

REMGATEID is the gate identifier and security code for the gate withinthat Edge Router.

CODING is the offered encapsulation methods and coding styles offered bythe call originator.

REFID is a unique identifier assigned by the originating GateController, which will appear in all the Billing Records. The REFID isintended to be unique within a period of several months.

BILLDATA is the billing/accounting data indicating the chargingarrangement for this conversation.

CINFO is a string generated by the originating Gate Controller thatcontains all the information needed for future enhanced services thatmay involve the call originator. This will be encrypted and given to thedestination BTI to store. The format is a list of many items separatedby slashes, or which the first is the ip address and port of the GateController that built the string. Subsequent items in this stringinclude the address/port of the Edge Router, gate identifier, signalingendpoint address, data endpoint address, the originator's call referencevalue, and the originator's address for initial call signaling.

7.9.1.1 GCSETUP Acknowledgment

When the terminating Gate Controller has completed the call, it packagesup all its assembled state information and passes it back to theoriginating Gate Controller in the GCSETUPACK message. A sampleGCSETUPACK message is:

GCSETUPACK 4T93177 v1.0; CRV 3712;

SIGADDR 135.207.22.1:6142; DATAADDR 135.207.22.1:6146 2 2; REMGATEIP135.207.22.1:7682; REMGATEID 21S11018;

CODING 53B,6 ms,G.711;

CINFO

135.207.31.2:7650/135.207.22.1:7682/21S11018/10.3.7.151:7685/10.3.7.151:7000-2-2/9733608766/3712/10.3.7.151:7685

CRV is the Call Reference Value assigned by the destination BTI for thisconversation. It is passed transparently from the SETUPACK message fromthe destination BTI.

SIGADDR is the IP address and port number the originator should use forBTI-BTI signaling messages. This is a global version of the addressgiven in the SETUPACK message from the terminating BTI, with name toip-address translation done, and with any NAT/PAT server translationincluded.

DATAADDR is the IP address and port number the originator should use fordata packets. This is a global version of the address given in theSETUPACK message from the terminating BTI, with name and ip-addresstranslation done, and with any NAT/PAT server translation included. Thesecond and third parameters (optional) in this element give the numberof consecutive ports used, and the alignment information needed for thestarting port number.

REMGATEIP is the IP address and port number of the Edge Router thatcontains the gate to be used at the terminating end for thisconversation. This is the destination address for all ER-ERcommunication.

REMGATEID is the gate identifier and security code for the gate withinthat Edge Router.

CODING is the encapsulation method and coding style accepted by the calldestination.

REFID (optional) is a unique identifier assigned by the Gate Controller,which will appear in all the Billing Records. The REFID is intended tobe unique within a period of several months. If this parameter appears,it will override the REFID assigned by the originating Gate Controller

BILLDATA (optional) is the billing/accounting data indicating thecharging arrangement for this conversation. If this parameter appears,it will override the BILLDATA assigned by the originating GateController.

CINFO is a string generated by the terminating Gate Controller thatcontains all the information needed for future enhanced services thatmay involve the terminating BTI. This will be encrypted and given to theoriginating BTI to store. The format is a list of many items separatedby slashes, or which the first is the ip address and port of the GateController that built the string. Subsequent items in this stringinclude the address/port of the Edge Router, gate identifier, signalingendpoint address, data endpoint address, the destination's callreference value, and the destination's address for initial callsignaling.

7.9.1.2 GCSETUP Error

If the terminating Gate Controller encounters an error while completinga connection request, it responds to the originating Gate Controllerwith a GCSETUPNAK message. A sample message is:

GCSETUPNAK 4T93177 v1.0; ERROR No gates available

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a SETUPNAK message.

Other elements in the message are TBD.

7.9.2 GCREDIRECT

The GCREDIRECT message is exchanged between Gate Controllers whendifferent Gate Controllers serve the originating and terminatingendpoints of a call. It is basically formed by packaging all the partialstate information the first Gate Controller has assembled in itsprocessing of a REDIRECT message, and requesting the terminating GateController to complete the work necessary to redirect the connection.

A sample GCREDIRECT message is:

GCREDIRECT OT5081 v1.0; DEST E164 9733608800;

BILLDATA 5123-0123-4567-8900/9733608718/9733608800;

CINFO

135.207.31.2:7650/135.207.31.1:7682/17S63224/10.0.12.221:7685/10.0.12.221:7000-2-2/9733608718/21/10.0.12.221:7685

DEST is the destination address for this new connection. Its format isthe same as in the SETUP message received from the BTI, except that theE164 number, if present, is expanded from the local numbering plan ofthe customer to the global numbering plan.

BILLDATA is the billing/accounting data indicating the chargingarrangement for the additional segment of this connection.

CINFO is a string generated by the originating Gate Controller thatcontains all the information needed for future enhanced services thatmay involve the call originator. This will be encrypted and given to thedestination BTI to store. The format is a list of many items separatedby slashes, or which the first is the ip address and port of the GateController that built the string. Subsequent items in this stringinclude the address/port of the Edge Router, gate identifier, signalingendpoint address, data endpoint address, the originator's call referencevalue, and the originator's address for initial call signaling.

7.9.2.1 GCREDIRECT Acknowledgment

If the terminating Gate Controller is able to successfully process aGCREDIRECT request, it responds with a GCREDIRECTACK message. A samplemessage is:

GCREDIRECTACK 0T5081 v1.0; REMGATEIP 135.207.22.1:7682; REMGATEID 21 S11018

REMGATEIP is the IP address and port number of the Edge Router that isholding a gate for the previous connection that has now been redirected.

REMGATEID is the identification string for the gate at that Edge Routerfor the previous connection.

7.9.2.2 GCREDIRECT Error

If the terminating Gate Controller encounters an error while completinga redirect request, it responds to the originating Gate Controller witha GCREDIRECTNAK message. A sample message is:

GCREDIRECTNAK OT5081 v1.0; ERROR No gates available

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a NAK message.

Other elements in the message are TBD.

7.9.3 GCSPLICE

If the Gate Controller receiving a SPLICE request from a BTI is not theone that generated the CINFO1 string, it sends to that Gate Controller aGCSPLICE message. A sample message of this type is:

GCSPLICE 7T1019 v1.0;

CINFO1

135.207.31.2:7650/135.207.22.1:7682/9S1077/10.3.7.151:7685/10.3.7.151:7006-2-2/9733608766/3746/10.3.7.151:7685;

CINFO2

135.207.31.2:7650/135.207.22.1:7682/5S71731/10.3.7.150:7685/10.3.7.150:7000-2-2/9733608720/8839/10.3.7.150:7685

If the Gate Controller receiving the above GCSPLICE request is not theone that generated the CINFO2 string, it sends to that third GateController another GCSPLICE message. A sample message of this secondtype is:

GCSPLICE 7T1021 v1.0;

CINFO2

135.207.31.2:7650/135.207.22.1:7682/5S71731/10.3.7.150:7685/10.3.7.150:7000-2-2/9733608720/8839/10.3.7.150:7685;SIGADDR 135.207.22.1:6162; DATAADDR 135.207.22.1:6164 2 2; CRV 3746;REMGATEIP 135.207.22.1:7682; REMGATEID 9S1077; CODING 53B,6 ms,G.71 1;REFID 135.207.31.2:26124C90:7224; BILLDATA6010-0203-0456-7890/9733608766/BRIDGE;

CINFO 135.207.31.2:7650/135.207.22.1:7682/9S1077/10.3.7.151:7685/10.3.7.151:7006-2-2/9733608766/3746/10.3.7.151:7685

CINFO1 is the string previously supplied by a Gate Controller, whichtells that Gate Controller various pieces of information about the firstendpoint. This string was stored encrypted by the BTI that originatedthe SPLICE request. Either CINFO 1 must be present in the message, orthe set of fields that are determined from the Gate Controller unpackingCINFO1: SIGADDR, DATAADDR, CRV, REMGATEIP, REMGATEID, CODING, REFID, andBILLDATA. With these fields present, the CINFO1 string is attached asCINFO.

CINFO2 is the string previously supplied by a Gate Controller, whichtells that Gate Controller various pieces of information about thesecond endpoint. This string was stored encrypted by the BTI thatoriginated the SPLICE request.

SIGADDR is the IP address and port number the second endpoint should usefor BTI-BTI signaling messages. This is a global version of the addressgiven in the SETUP/SETUPACK message from the first endpoint BTI, withname to ip-address translation done, and with any NAT/PAT servertranslation included.

DATAADDR is the IP address and port number the second endpoint shoulduse for data packets. This is a global version of the address given inthe SETUP/SETUPACK message from the first endpoint BTI, with name andip-address translation done, and with any NAT/PAT server translationincluded. The second and third parameters (optional) in this elementgive the number of consecutive ports used, and the alignment informationneeded for the starting port number.

REMGATEIP is the IP address and port number of the Edge Router thatcontains the gate to be used at the first BTI's end for thisconversation. This is the destination address for all ER—ERcommunication.

REMGATEID is the gate identifier and security code for the gate withinthat Edge Router.

CODING is the encapsulation method and coding style accepted by thefirst BTI.

REFID is a unique identifier assigned by the Gate Controller, which willappear in all the Billing Records. The REFID is intended to be uniquewithin a period of several months.

BILLDATA is the billing/accounting data indicating the chargingarrangement for this conversation.

CINFO is a string generated by a Gate Controller that contains all theinformation needed for future enhanced services that may involve thatBTI. This will be encrypted and given to the other BTI to store. Theformat is a list of many items separated by slashes, or which the firstis the ip address and port of the Gate Controller that built the string.Subsequent items in this string include the address/port of the EdgeRouter, gate identifier, signaling endpoint address, data endpointaddress, the destination's call reference value, and the destination'saddress for initial call signaling.

7.9.3.1 GCSPLICE Acknowledgment

If the terminating Gate Controller is able to successfully process aGCSPLICE request, it responds with a GCSPLICEACK message. If theGCSPLICE request was of the first type above, a sample acknowledgementmessage is:

GCSPLICEACK 7T1019 v1.0;

If the GCSPLICE request was of the second type above, a sampleacknowledgment message is:

GCSPLICEACK 7T1021 v1.0;

SIGADDR 135.207.22.1:6166; DATAADDR 135.207.22.1:6168 2 2; CODING 53B,6ms,G.711;

REMGATEIP 135.207.22.1:7682; REMGATEID 5S71731; CRV 8839; REFID135.207.31.2:26124C90:7224;

BILLDATA 6010-0203-0456-7890/9733608720/9733608766;

CINFO

135.207.31.2:7650/135.207.22.1:7682/5S71731/10.3.7.150:7685/10.3.7.150:7000-2-2/9733608720/8839/10.3.7.150:7685

SIGADDR is the IP address and port number the first endpoint should usefor BTI-BTI signaling messages. This is a global version of the addressgiven in the SETUP/SETUPACK message from the second endpoint BTI, withname to ip-address translation done, and with any NAT/PAT servertranslation included.

DATAADDR is the IP address and port number the first endpoint should usefor data packets. This is a global version of the address given in theSETUP/SETUPACK message from the second endpoint BTI, with name andip-address translation done, and with any NAT/PAT server translationincluded. The second and third parameters (optional) in this elementgive the number of consecutive ports used, and the alignment informationneeded for the starting port number.

REMGATEIP is the IP address and port number of the Edge Router thatcontains the gate to be used at the second BTI's end for thisconversation. This is the destination address for all ER—ERcommunication.

REMGATEID is the gate identifier and security code for the gate withinthat Edge Router.

CODING is the encapsulation method and coding style accepted by thesecond BTI.

REFID (optional) is a unique identifier assigned by the Gate Controller,which will appear in all the Billing Records. The REFID is intended tobe unique within a period of several months. If this parameter appears,it will override the REFID assigned by the originating Gate Controller

BILLDATA (optional) is the billing/accounting data indicating thecharging arrangement for this conversation. If this parameter appears,it will override the BILLDATA assigned by the originating GateController.

CINFO is a string generated by a Gate Controller that contains all theinformation needed for future enhanced services that may involve thatBTI. This will be encrypted and given to the other BTI to store. Theformat is a list of many items separated by slashes, or which the firstis the ip address and port of the Gate Controller that built the string.Subsequent items in this string include the address/port of the EdgeRouter, gate identifier, signaling endpoint address, data endpointaddress, the destination's call reference value, and the destination'saddress for initial call signaling.

7.9.3.2 GCSPLICE Error

If the terminating Gate Controller encounters an error while completinga splice request, it responds to the originating Gate Controller with aGCSPLICENAK message. A sample message is:

GCSPLICENAK 4T93177 v1.0; ERROR No gates available

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so, and can be passed back to theBTI in a NAK message.

Other elements in the message are TBD.

7.10 Edge Router to Billing Event Collector

Messages sent by the Edge Router include CALLSTART, CALLEND, andCALLPARTIALEND. These messages are sent over a reliable transportmechanism, such as TCP/IP, which performs all of the flow control anderror control needed to ensure the reliable receipt of the messages atthe Billing Event Collector. The format of the messages is slightlydifferent than other messages, since they are not transaction based.

These messages must also include a timestamp. It is assumed here thatthe timestamp will be added by the Billing Event Collector, who willperform its function in real-time. If, however, the Edge Routers areexpected to accumulate event records for some longer period of time andsend them in a burst, then the Edge Router will need to record the timeof each event and the messages must include that information as well.

7.10.1 CALLSTART

Whenever an Edge Router allocates resources for a gate, it issues aCALLSTART event record to the Billing Event Recorder. A sample messageis:

CALLSTART 135.207.31.2:36123E5C:931785123-4567-8900/9733608718/8733608766 53B,6 ms

The parameters to this message are:

1) The unique reference ID for this call, which will be common in allbilling records related to the call

2) The billing data for this call, which consists of multiple sets ofthree items:

a) the account number to be charged for the call

b) the source E. 164 number for the call

c) the termination E. 164 number for the call

d) the above three fields repeated as needed for multiple call segment

3) The bandwidth resources used by this call.

7.10.2 CALLEND

Whenever an Edge Router releases resources for a gate, it issues aCALLEND event record to the Billing Event Recorder. Note that this doesnot occur when a call is placed on HOLD, since the resources are stillreserved for future use. A sample message is:

CALLEND 135.207.31.2:36123E5C:93178 5123-4567-8900/9733608718/873360876653B,6 ms

The parameters to this message are:

1) The unique reference ID for this call, which will be common in allbilling records related to the call

2) The billing data for this call, which consists of multiple sets ofthree items:

a) the account number to be charged for the call

b) the source E.164 number for the call

c) the termination E. 164 number for the call

d) the above three fields repeated as needed for multiple call segment

3) The bandwidth resources used by this call.

7.10.3 CALLPARTIALEND

Whenever an Edge Router is instructed by a Gate Controller to releasesresources at one end of a conversation, but told not to coordinate withthe remote gate and release all the resources at both ends, it issues aCALLPARTIALEND event record to the Billing Event Recorder. A samplemessage is:

CALLPARTIALEND 135.207.31.2:36123 E5C:931785123-4567-8900/9733608718/8733608766 53B,6 ms

The parameters to this message are:

1) The unique reference ID for this call, which will be common in allbilling records related to the call

2) The billing data for this call, which consists of multiple sets ofthree items:

a) the account number to be charged for the call

b) the source E.164 number for the call

c) the termination E.164 number for the call

d) the above three fields repeated as needed for multiple call segment

3) The bandwidth resources used by this call.

7.11 Gate Controller to NAT/PAT Server

Messages sent by the Gate Controller include NATENQ, and NATSETUP.

Inquiry messages to the NAT/PAT server have a common structure formessage element names. The first letter of the type name is either “L”or “G”, indicating a request about a local or global address. The lastportion of the type name is a number, which is used by the sender tomatch up responses with the requests. For example, a request messagewith a parameter GADDR3 will give a response with a parameter LADDR3,and a request message with a parameter LADDR7 will give a response witha parameter GADDR7. There is no requirement that the digit sequences inparameter names by consecutive, but they must be unique within themessage.

7.11.1 NATENQ

A NATENQ message is sent by the Gate Controller to the NAT server toinquire about a possible entry in the translation tables, but withoutcreating an entry if none currently exists.

A sample message is:

NATENQ 4T93174 v1.0; LADDR1 10.0.12.221:7685

LADDRx/GADDRx is the locauglobal address and port number that the GateController is asking about.

7.11.1.1 NATENQ Acknowledgment

The response to a NATENQ message gives the translations found in thetables for the specified addresses. If no entry was found, its elementis not present in the response message. A sample NATENQACK message is:

NATENQACK 4T93174 v1.0; GADDR1 135.207.31.1:6000

GADDRx/GADDRx is the global/local address and port number that the GateController is asking about.

7.11.1.2 NATENQ Error

The only anticipated error that can occur in a NATENQ message is thatthe server does not perform a NAT/PAT function, and therefore does notrecognize the request. A sample error response is:

NATENQNAK 4T93174 v1.0; ERROR Unrecognized request

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so. Otherwise it provides someuseful debugging information. It can also be passed back as part of theerror indication from the Gate Controller request.

Other elements in the NATENQNAK message are TBD.

7.11.2 NATSETUP

A NATSETUP message is sent by the Gate Controller to the NAT server tocreate entries in the translation tables. A sample message is:

NATSETUP 4T93175 v1.0; LADDR1 10.0.12.221:7685; LADDR2 10.0.12.221:70002 2

LADDRx/GADDRx is the local/global address and port number that the GateController desires entries to be established in the translation table.The second parameter, if present, gives the number of consecutive portsrequested. The third parameter, if present, gives any alignmentrestrictions on the port number assigned.

7.11.2.1 NATSETUP Acknowledgment

The response to a NATSETUP message gives the translation entries eitherfound or established in the translation tables. A sample NATSETUPACKmessage is:

NATSETUPACK 4T93175 v1.0; GADDR1 135.207.31.1:6000; GADDR2135.207.31.1:6002 2

GADDRx/GADDRx is the global/local address and port number that the GateController asked to be established. The second parameter (if present)indicates the number of consecutive ports assigned.

7.11.2.2 NATSETUP Error

Any error encountered while creating NAT/PAT entries will result in aNATSETUPNAK message. A sample error response is:

NATSETUPNAK 4T93175 v1.0; ERROR Translation table full

ERROR gives an error message string, which could be displayed if theGate Controller has some method to do so. Otherwise it provides someuseful debugging information. It can also be passed back as part of theerror indication from the Gate Controller request.

Other elements in the NATSETUPNAK message are TBD.

7.12 NAT/PAT Server to Gate Controller

No messages are initiated by the NAT/PAT server.

8 Signaling Architecture Call Flows

In this section call flows are presented to show the signaling exchangefor both basic telephony services as well as many CLASS and CustomCalling features. This section is substantially identical to thecorresponding section of the present U.S. patent application, Ser. No.09/366,207 filed Aug. 4, 1999 and allowed on Feb. 11, 2002, which ishereby incorporated by reference.

8.1 Call Flow Terminology

The following terminology describes signaling call flows that can beused by embodiments of the present invention. Symbols are used torepresent parties involved in the call flow (e.g. Gate Controllers) andinformation that is exchanged (e.g. Call Parameters). Each of these isoften followed by a subscript indicating which one specifically is beingreferenced. Common subscripts are O for originating, T for terminating,F for forwarding, B for bridging, and TR for transferring. For example,in a simple telephone conversation, BTI_(O) refers to the originatingBTI, and BTI_(T) to the terminating BTI, and similarly for E.164_(T),ER_(O), ER_(T), GC_(O), GC_(T), etc.

All the messages and parameters are described in detail in the nextsection.

Call Flow Symbols:

BTI—Broadband Telephony Interface—or a telephony-equipped cable modem

ER—Edge Router: Cable modem termination system that serves the BTI

GID—Gate ID: Identification of the “gate” within the edge routerassigned to this call.

GC—Gate Controller that serves the BTI

CI—Call Information: Information about the call through the network.This information includes the E. 164 address, the IP address of the BTI,the IP address of the serving Gate Controller, the IP address of theserving ER, and the GID of the gate in the ER.

[CI](GC)—Encrypted information about the BTI that is given to othersoutside the network to store. It is signed and encrypted by the GateController indicated.

BID—Billing ID: Identifier of the call for billing purposes; intended tobe unique not only within the entire network, but to not be reused for asignificant period of time. Both Edge routers involved in a call reportthis identifier in the call detail records.

TID—Transaction ID: Identifier of a message; indended to only be locallyunique for the duration of a message/response transaction.

E.164—Telephone number

CN—Directory name of caller

LA—local IP address (set when BTI powers on)

GA—global IP address (set via NAT when BTI begins a session)

PN—Port number used by BTIs for a particular connection

AI—Authentication Information, single string per subscriber, commonacross all lines served by one BTI. This string is signed and encryptedby a network server, and is verified by Gate Controllers for everytransaction.

$—call accounting information, such as customer account number, to beincluded in billing information for the current call. Given to ER aspart of the permission to open gate. In some cases, e.g. callforwarding, two separate account numbers will be included to indicate asplit charging arrangement for the call. In addition to charginginformation, accounting information includes parameters that placebounds on the call that is to be established. Some parameters mayinclude maximum call duration and transmission priority.

CP—Call parameters (e.g. compression standard) for this call. CPO arethe parameters offered by the call originator, CPT are those accepted bythe terminating system.

o—indicates that network address translation is done in the ER

ANN-INFO—Announcement Information: Parameter indicating to anannouncement server which announcement to play.

CF—Flag that indicates call forwarding on all calls or busy is active.

T—Flag that indicates call transfer is active.

CTOR—Cut Through On Release Flag: Indicates that the Edge Router shouldcut through the call in the receive direction when the BTI reserves thebandwidth.

SGCP Parameters:

S-R—SGCP parameter indicating a connection should be opened in both thesend and receive directions.

S-NR—SGCP parameter indicating a connection should be opened only in thesend (upstream) direction.

NS-R—SGCP parameter indicating a connection should be opened in only thereceive (downstream) direction.

SS7 Symbols:

IAM—Initial Address Message

ACM—Address Complete Message

E-ACM—Early Address Complete Message

ANM—Answer Message

REL—Release Message

RLC—Release Complete Message

SUS—Suspend Message

RES—Resume Message

8.2 Basic Call Flows

8.2.1 Connect

FIG. 6 shows the call flow for a normal call setup. Call setup involvesestablishing an IP signaling and bearer channel between BTIs across apacket network. The signaling channel uses “better than best effort” IPtransmission across the network. Signaling reliability is ensured withinthe application. In the access portion of the network (between the edgerouter [ER] and the BTI), the bearer channel uses an “unsolicited grant”as defined by the MCNS v1.1 to maintain a constant bit rate channel. TheER “colors” the “high QoS” bearer channel packets to give them higherpriority than “best-effort QoS” packets over the backbone portion of thenetwork (between the ERs).

Some of the aspects of the basic Connect call flow are:

Digit Collection—The BTI_(o) needs to recognize when a completetelephone number is dialed so it can package the number in a SETUPmessage and send it on to GCo for translation.

Network Address Translation (NAT) for the Originating BTI—The ER doesnetwork address translation between local (Net10) addresses for each ofthe BTIs and global addresses. Each ER is assigned a set of globaladdresses. The ER assigns a global address to a BTI when the BTIattempts to communicate outside of its local area, or when a GateController requests that a global address be assigned to a BTI.

BTI Authentication—GC_(O) authenticates the BTI upon receipt of a SETUPmessage. The Authentication Information (AI) needs to be provisioned inthe BTI at BTI registration. GC_(O) also performs service-specificadmission control. For instance, if a Gate Controller knew that aspecific destination area was overloaded with traffic, it could block acall setup.

Gate Allocation—GC_(O) requests a gate be allocated in ER_(O) for thiscall. ER_(O) replies with a Gate ID (GID_(O)) to be used for the call.GC_(O) adds this information to the Call Information (CI_(O)) record forthis call.

Billing Identifier (BID)—While processing an initial call attempt, theGate Controller assigns a globally unique Billing Identifier (BID) tothe call. Such a unique identifier could be, for example, the IP addressof the Gate Controller, followed by a timestamp, followed by a callsequence number. It is intended that this identifier be unique overseveral billing cycles, and enable the billing system to correctly matchall records related to a single call.

Number Translation—The E.164_(T) address is translated by the GateControllers to the local IP address of the terminating BTI and theterminating ER. If GC_(O) cannot translate the E.164_(T) address on itsown, it identifies a Gate Controller (GCT) that can do the translation.GC_(O) sends the GCSETUP message, with additional information in it, onto GCT for processing. This simplifies the security of the ER, in thatit only accepts commands from a small group of well-known GateControllers.

Accounting Information ($)—In addition to charging information (e.g.account number), accounting information includes parameters that placebounds on the call that is to be established. Some parameters mayinclude maximum call duration and transmission priority. In severalsituations involving call forwarding, the charging for the call will besplit among two or more subscribers. Thus the “$” parameter in messagesmay contain several account codes with information as to the properallocation of charges to each.

“Opening The Gate”—The Gate Controller gives permission for an ER toallow a BTI to set up an “unsolicited grant”. The ER also “colors” thebearer-channel packets so they have “high-QoS” to a specific destinationaddress. If an ER does not receive the permission to “open the gate” forhigh-priority packets, it does not allow the unsolicited grant or thehigh-priority packets. This permission is based on a specific source IPaddress and a specific destination IP address, and bounds on theresources the endpoints can use. The account information ($) in the gatesetup message to the ER provides the bounds on these resources.

Call Information (CI_(O) and CI_(T))—information about a BTI, includingits E.164 address, its Gate Controller's address, its ER's address, andthe GID within the ER. Each endpoint of a call receives this informationabout the other endpoint, signed and encrypted by the local GateController to prevent unauthorized disclosure or tampering by the BTI.This call information is used later for Call Trace (*57), Call Return(*69), and in setting up Three-Way Calling.

Capability Negotiation—The BTIs have the ability to negotiate CallParameters (CP) (e.g. encoding) in the SETUP message exchange. Ifadditional negotiation is needed, it can be accomplished before resourcecommitment is made.

Access Resource Reservation—An MCNS unsolicited grant protocol is usedto reserve a constant bit rate channel in the access portion of thenetwork. The access reservation comes in two parts, which is requiredfor the telephony application. In first step, the “reservation” ensuresthe bandwidth will be available when needed, but does not actuallyassign the bandwidth nor does it “open the gate.” The reservation isobtained prior to ringing the destination telephone. Only when thedestination user answers does the second step, the “commitment,”allocate the bandwidth and start the billing for the call. To protectresources, only a certain number of outstanding reservations are allowedper BTI.

Backbone Resource Reservation—Embodiments of the present invention allowfor the possibility of a different backbone resource reservationprotocol than that used for the access portion of the network. It is thejob of the ER to process the access reservation message and translanteit into the proper message sequence for backbone resources. When the ERacknowledges the reservation with an ACK message, it means that theaccess resources are available for the call and whatever backboneresources this CMTS needed to reserve to support the flow has beenreserved. At this point it is safe to begin the ring phase. An exampleof backbone resource reservation is shown in Section 8.2.2.

Commit—This is the second step of the access reservation sequence. Thecommitment is made when an actual connection is to be made and billingis started. The ER and the network previously reserved the resources,and held them for this particular conversation. The ER emits acall-detail-record to the billing system at this time.

Gate Coordination—In order to avoid certain theft of service scenarios,the opening and closing of gates within the network needs to becoordinated between ERs. GATEOPEN is an ER to ER message indicating thatthe gate has opened on the far end of the call. Far end Call Parametersare passed to the BTI for it to check whether it agrees with theparameters that are in the far end gate.

8.2.2 Backbone Reservation

FIG. 7 shows an example signaling flow for reservation of resources inthe segment of the network between the edge routers for a voice call.This is one potential model of backbone reservation; however, differentapproaches may achieve the same result. One principle that we desire toachieve is to separate the mechanism for access reservation from thebackbone reservation. This leaves the BTI interaction with the ERindependent of the backbone network between ERs.

We assume a model in which the resource reservation is initiated by asender and only reserves resources for packets being generated by thatsender i.e. reservations are unidirectional. This matches the forwardingmodel used in IP networks in which paths can be asymmetric. However, theRESERVE message used over the access network has different semantics:reserve bi -directional capacity over the access network.

Since, the end to end route between two edge routers may change duringthe duration of a call, we also assume that RESERVE messages areperiodically transmitted from either end to refresh the reservation—thisis not shown in the figure. The IP source address in the RESERVE messagecontains the source address of ER_(O). The IP destination address in theRESERVE message is that of BTI_(T). The reservation message identifies:GA_(O) (BTI_(O)'s global IP address), PN_(O) (BTI_(O)'s port number forthis call), GA_(T) (BTI_(T)'s global IP address), PN_(T) (BTI_(O)'s portnumber for this call) as the owner of the reservation. After setting upthe bidirectional access reservation, the ER sends a BACKBONERESERVEmessage through intermediate backbone routers towards BTI_(T). Routersthat are incapable of processing the BACKBONERESERVE message forwardthem without any processing.

In this example, the receipt of the RESERVEACK to a BTI indicates thatresources have been reserved in both the send and receive directions inthe access channel, and in the send direction in the backbone.

8.2.3 Disconnect

FIG. 8 shows the call flow for a normal call termination. When a BTIdetects on-hook, it sends an end-to-end HANGUP message to the other BTIand a RELEASE message to the ER. In response to the RELEASE command, theER closes the gate and emits a CALLEND to the billing system thatindicates the call has completed and that billing should stop.

Note that there are a number of error conditions that will cause thisdisconnect sequence, such as BTI failures, power failures, cable plantfailures, and backbone network failures. In all cases, it is desirableto stop the billing at the end of the useful connection, and to notcharge the customer for a (possibly lengthy) service outage.

8.2.4 Calls Terminating in the PSTN

FIG. 9 shows the call flow for a call originating from a BTI butterminating in the PSTN. In the call flow, GC_(T) recognizes thatE.164_(T) terminates outside of the IP network. GC_(T) identifies theappropriate SGW_(T) and TGW_(T). GC_(T) initiates a GATESETUP to ER_(T)with the Cut Through On Reserve (CTOR) flag set to indicate that aone-way voice path from the PSTN to BTI_(O) should be established oncethe reserve is requested. GC_(T) then sends the SETUP to SGW_(T).SGW_(T) allocates a trunk identified by the IP port number PNT onTGW_(T) for the call. SGW_(T) also looks at CP_(O) to determine the callparameters that will be used for this call (CPT).

Upon receiving the SETUPACK from SGW_(T), GC_(T) replies to GC_(O),including the CTOR flag. GC_(O) sets up the gate on the originating endof the call including the CTOR flag indicating that ER_(O), should openthe voice path toward BTI_(O) on reserve. GC_(O) also includes the CTORflag on the SETUPACK message to BTI_(O) so BTI_(O) does not generate itsown ringback, but uses the ringback from the far end of the network. Ifadditional capability negotiation is needed, it can be done at thispoint.

Once the call parameters are known, SGW_(T) uses the SGCP messageCREATECONNECTION to inform TGW_(T) about the potential call. Included inthis message are all the parameters that TGW_(T) needs to reserve thenecessary bandwidth and to translate between the IP packets and the TDMtrunk. Also included in this message is an SGCP NOTIFICATIONREQUEST,requesting TGW_(T) to notify SGW_(T) when the reservation isacknowledged by ER_(T). TGW_(T) sends a reserve message requesting theappropriate QoS in the network for the call. The trunking gateway needsto send this reserve message (versus the SGW) since the reservationneeds to be along the path of the bearer channel. Upon a successfulreservation, TGW_(T) sends the SGCP NOTIFY to SGW_(T).

Once SGW_(T) receives both the RING message from BTI_(O) and the NOTIFYfrom TGW_(T), SGW_(T) sends the SS7 Initial Address Message (IAM) intothe PSTN to set up the connection between TGW_(T) and the ultimatedestination. Upon receipt of the SS7 Address Complete Message (ACM),indicating that the destination phone is available and ringing, SGW_(T)sends BTI_(O) the RINGBACK message and BTI_(O) plays ringback tone it isreceiving from the network to the customer.

When the destination phone goes off-hook, an SS7 Answer Message (ANM) isreceived by SGW_(T). SGW_(T) sends the CONNECT back to BTI_(O) and usesthe SGCP message MODIFYCONNECTION to indicate to TGW_(T) that it needsto change the connection to a two-way connection, and send the COMMITinto the network to open the gate in both directions.

There are special cases when SS7 messages are received that cause thecall flow to change. Some of these cases are described below:

Early Address Complete Message (E-ACM)—When an E-ACM message is receivedfrom the SS7 network instead of ACM, the voice connection needs to beestablished in both directions (send and receive). One example of howthis is used by the PSTN is to indicate when an 800 call is being routedto an IVR system to determine where the call should be ultimatelyrouted. After the call is routed and the far end answers, SGW_(O)receives an ANM.

Busy—If either the PSTN network or the called party is busy, the SS7network returns a busy indication with a cause code in response to theIAM. SGW_(O) needs to send a BUSY message with a cause code in place ofRINGBACK to BTI_(O) so BTI_(O) will play fast busy or slow busy to thecustomer.

8.2.5 Calls Originating from the PSTN

FIG. 10 shows the call flow for a call originating in the PSTN, butterminating in the IP telephony network. The IAM message is the firstindication that a call is destined from the PSTN to a BTI. The IAMmessage is received by SGW_(O) which subsequently sends a SETUP messageto GC_(O). setup proceeds as normal through the IP network. The CTORflag is not needed since ringback or terminating announcements will notbe generated from the IP network.

The signaling flow is similar to when a call is destined for the PSTN(see previous section). SGCP messages are used between SGW_(O) andTGW_(O).

8.2.6 Call Release to the PSTN

FIG. 11 shows the call flow for a normal release to the PSTN. This callflow assumes that the BTI originated the call. If the call originated inthe PSTN, SGW_(T) would send an SS7 Suspend (SUS) message. Thisindicates to the PSTN that the phone at the BTI went on-hook, but thecall is not released until a timer expires (usually 14 seconds). If thephone goes off-hook before the timer expires, an SS7 Resume (RES)message is sent.

8.2.7 Call Release from the PSTN

FIG. 12 shows the call flow for a call released from the PSTN. The callflow assumes that the call originated in the PSTN.

8.2.8 E911 Emergency Service

To support E911 emergency calls, GC_(O) must route the call to the E911call center associated with the calling number. The E911 call center maybe reached via a gateway or may be an E911 call center that is supportedon the packet network. The originating phone number and additionalinformation can be obtained by having the E911 call center send aSETUPNACK message to GC_(T) as in the call flows for caller ID/callingname delivery. Otherwise, the call flows for call setup are unchanged.

The BTI originating a 911 call must not disconnect the call when theuser hangs up. This requires BTI_(O) to detect that the dialed number is911 and to alter its local hangup processing accordingly.

A call to an operator for assistance may be transferred by the operatorto an E91 1 center. In this case, the gateway or end-system that theoperator is connected to must send an end-to-end message to BTI_(O)instructing it to alter its hangup processing. This message must beauthenticated by BTI_(O) as being sent by a trusted network entitybefore BTI_(O) alters its hangup processing. Authentication is requiredso that an arbitrary endpoint cannot instruct a BTI to alter its hangupprocessing.

8.2.9 Terminating Announcements

In some cases when a call cannot be completed, the customer hears aterminating announcement. Terminating announcement handling may beinvoked when the dialed number has changed or cannot be translated, oras a result of a network resource limitation (e.g., “trunk busy”) ornetwork problem.

Since the BTI contains processing and storage, common terminatingannouncements may be handled locally by the BTI in response to an errorindication. For example, common messages such as “The number you havedialed is not in service. Please check the number and dial again” or the“trunk busy” signal may be stored locally in the BTI. In the first case,GC_(O) returns an error message to BTI_(O) indicating that the dialednumber cannot be translated. In the second case, a router returns anerror message to BTI_(O) as a result of an admission control failureduring the processing of a COMMIT message. The error messages indicateto BTI_(O) which announcement should be played.

Some services require the announcement to be customized, perhaps basedon the originating number, dialed number, time-of-day, or administrativecontrols. Thus, in general, announcements are a function of conditionsknown to the Gate Controller. In this case, there are two options forsupporting terminating announcements. The Gate Controller may send theannouncement to the BTI as a data message to be played out by the BTI.Alternatively, the BTI may connect to a terminating announcement server.These alternatives may also be used to support the common terminatingannouncements described above.

FIG. 13 shows a call flowwhere the BTI connects to a terminatingannouncement server.

Terminating announcement handling may be invoked either by GC_(O) or GCTin response to a SETUP message. The Gate Controller routes the call to aterminating announcement server and interacts with the server to controlthe announcement that it plays. The call accounting information (“$”)that is used for the call indicates that the call is not billed.

8.2.10 CALEA Wiretapping

CALEA requires the ability to intercept (wiretap) calls from asubscriber line and to provide additional information associated withthese calls, such as the dialed number, and the time and duration of thecall. Given that the BTI is not considered to be a trusted device,support for CALEA wiretapping must be implemented within the network,and must not be detectable by any party participating in the call. Oursolution to the problem requires the ER to be able to multicastinformation flowing from each party in the call to both the other partyor parties, and an additional end-system or gateway (a “wiretap server”)that can deliver the bearer channel information to the authorities. Thismulticast capability requires every packet that matches a filterfunction to be routed to the wiretap server, in addition to being routednormally. The filter function is discussed below.

One proposed approach to the problem does not rely on per-connectionprocessing in the ER to wiretap a line. In this approach, when theauthorities ask that a line be wiretapped, an administrative systemsends a message to the originating ER instructing it to multicast thebearer channel to the wiretap server. The filter specifies the local IPaddress of the BTI associated with the line that is being tapped, theaddress of the wiretap server, and it might additionally specify theport number associated with the bearer channel. However, since the portnumbers associated with the bearer (voice) channel may be dynamicallyassigned by the originating and terminating BTI's, the administrativeserver is unable to specify this information. If the filter functiondoes not contain the port number information, it would cause all packetsassociated with the BTI to be intercepted, which may not be desirablesince these packets may include data packets that cannot legally beintercepted. Thus, this approach is possible in our architecture, but itmay be desirable to have an approach that only intercepts the bearerchannel without intercepting additional channels.

The preferred approach is to rely on the Gate Controller to supportwiretapping. When the authorities ask that a line be tapped, thedatabase record associated with the line is modified to indicate thatthe line should be tapped. When a SETUP message arrives at the GateController (it may be either an originating Gate Controller or aterminating Gate Controller), the Gate Controller looks up the databaserecord and notes that the line should be tapped. The Gate Controllersends a message containing the address of the wiretap server to the ER.This information may be included as part of the “gate open” message.

The Gate Controller also sends a message containing the dialed number tothe wiretap server. The ER sends messages at the beginning and the endof the call to the wiretap server. These additional messages provide theadditional information required by CALEA. In this solution, only newcalls may be wiretapped. Calls that exist before the wiretappinginformation is provisioned in the GC will not be multicast to thewiretap server.

8.2.11 Call Trace

FIG. 14 shows the call flow for Call Trace. BTI_(T) (the recipient ofthe call that needs to be traced) sends a single TRACE message toGC_(T), containing its own authentication information, and theconnection information received from GC_(T) for the most recent incomingcall. GC_(T) verifies the connection information (CI) by decrypting andchecking the signature. If valid, the E.164 number contained within CIis reported to law enforcement, along with the identity of the customermaking the report.

8.2.12 Operator Break-In

Operator Break-In is a combination of the CALEA wiretapping described inSection 8.2.10 and Three-Way Calling described in Section 8.3.4. Callflows for operator break-in will be provided in future versions of thisdocument.

8.2.13 Operator Services

Operator services will initially be supported for IP phone customers bygoing through a PSTN Gateway. In the future, operator services may be onthe IP network.

8.2.14 Mid-Call Resource Change

In some cases, a call in progress may need to change the establishedcall parameters. For instance, if a call is set up using a low-bit-ratecompression (e.g. 16 kbps G.728) and after the call is answered the BTIdetects a modem tone, the BTI needs to change the bearer channel to anon-compressed 64 kbps G.711 channel. FIG. 15 shows the call flow of howthis can be accomplished. Gate Controllers do not need to be involved ina mid-call resource change as long as the account information the GateController delivered to the ER during call set up is consistent with theresource change request. For example, if the BTI requests a channel withhigher bandwidth or higher priority than the account information allows,the ER would deny the request. As with the normal call set up, there isa two step—Reserve then Commit—process for changing call parametersmid-call.

8.3 Feature Call Flows

8.3.1 Call Forwarding

Call Forwarding service allows a call destined for one E.164 address tobe redirected to another E.164 address. The redirection may happen onall calls, only on busy, only on no answer, or on a combination ofeither busy or no-answer. Call Forwarding is a popular service, and isused by other services (e.g. voice mail) to redirect calls. If a BTI isunavailable and call forwarding is active, all calls destined for theBTI should be forwarded.

At least three parties are involved in all types of Call Forwardingservice:

The Originating Location (BTI_(O))—the location that places the call tobe forwarded.

The Terminating Location (BTI_(T))—the location that has Call Forwardingactive.

The Forwarding Location (BTI_(T))—the location that the calls are beingforwarded to.

Regardless of the type of Call Forwarding (All Calls, Busy, No Answer),the forwarding number may be specified by the customer on a per-usebasis, or be pre-provisioned (specified when the customer signs up forCall Forwarding service). If the forwarding number is pre-provisioned,the BTI and the Gate Controller serving that customer stores theforwarding number. If the forwarding number is specified on a per-usebasis, the customer dials a code (e.g. *72) and the forwarding number toactivate Call Forwarding.

In all cases, the Originating Location must not receive the forwardingnumber. In the case of Call Forwarding—No Answer, the OriginatingLocation may know that the call is being forwarded.

FIG. 16 shows the call flow for activating a per-use Call Forwardingservice. The BTI recognizes that the customer dialed the code to activeCall Forwarding, and prompts the customer for the forwarding telephonenumber. This information is sent to the Gate Controller in a PROFILEmessage. The Gate Controller validates that the forwarding number mapsto either a BTI that the Gate Controller knows or to another GateController. The Gate Controller checks to make sure the customersubscribes to Call Forwarding service, and if so activates the serviceand stores the forwarding number for later use.

The following sections describe the call flows for each of the types ofCall Forwarding service for both when the BTI is available and when theBTI is unavailable.

8.3.1.1 Call Forwarding—All Calls

FIG. 17 shows the call flow for Call Forwarding—All Calls when the BTIis available. The first part of the call flow is the same as shown inFIG. 6: Connect Call Flow. When the SETUP message is received by theTerminating BTI, it recognizes that Call Forwarding—All Calls is active.It sends a special SETUPACK to the Terminating Gate Controllerindicating that Call Forwarding is active. The Gate Controllerrecognizes the Call Forwarding response, closes the gate at the ER thatit opened for this call (using the GATERELEASE message), and sends theforwarding number on to GC_(O) along with account information so thatthe forwarded leg of the call can be billed to BTI_(T). The OriginatingGate Controller sets up the call to the forwarding number as normal,except that billing information may be kept for both legs of the call.

FIG. 18 shows the call flow for Call Forwarding—All Calls when theTerminating BTI is not available. In this case, GC_(T) times out on theBTI_(T) SETUP message. The GC_(T) checks the customer profile anddetermines that Call Forwarding is active and proceeds as if it got aCall Forwarding response from BTI_(T).

8.3.1.2 Call Forwarding—Busy

FIG. 19 shows the call flow for Call Forwarding—Busy when BTI_(T) isavailable. The first part of the call flow is the same as shown in FIG.6: Connect Call Flow. When the SETUP message is received by BTI_(T), itrecognizes that the designated line is currently off-hook and that CallForwarding—Busy is active. It sends a special SETUPACK to GC_(T)indicating that Call Forwarding is active. GC_(T) recognizes the CallForwarding response. The rest of the call flow is identical to FIG. 17:Call Forwarding—All Calls/BTI Available.

FIG. 20 shows the call flow for Call Forwarding—Busy when the BTI isunavailable. This flow is identical to FIG. 18: Call Forwarding—AllCalls/BTI Unavailable Call Flow.

8.3.1.3 Call Forwarding—No Answer

FIG. 21 shows the call flow for Call Forwarding—No Answer when BTI_(T)is available. The first part of the call flow is the same as shown inFIG. 6: Connect Call Flow. BTI_(T) recognizes the Call Forward-No Answerfeature is active and times out after the correct number of rings. ARINGTIMEOUT message is sent to the originator to stop the ringback, anda REDIRECT message is sent to the GC_(T) to start the forwardingoperation. The REDIRECT message contains the new E.164F address.

GC_(T) decrypts the call information, and retrieves the billinginformation for this subscriber. If the call forwarding or transferfeature is subscribed it passes the GCREDIRECT message back to theGC_(O) with the appropriate billing information.

The REDIRECT messages serves two purposes, this call forwarding functionand also a blind transfer function (transfer without consultation).Since the Gate Controller does not know which application is active, itmust assume a data transfer is in progress and inform BTI_(O) that itwill be interrupted. This is done via the CALLHOLD/CALLHOLDACK exchange.If BTI_(O) was in a talking state, BTI_(O) tells ER_(O) to temporarilysuspend its resource reservation; then acknowledges the CALLHOLD commandof the GC_(O). GC_(T) then acknowledges to BTI_(T) that the REDIRECT wassuccessful.

At this point the GC_(O) treats this call identically to the initialcall, by translating E.164F into a Gate Controller address and passing aGCSETUP message to GC_(F). The actions of GC_(F), ER_(F), and BTI_(F)are identical to those shown in FIG. 6 for GC_(T), ER_(T), and BTI_(T).

When GC_(O) receives the acknowledgement to its GCSETUP message, insteadof performing a GATESETUP it modifies the settings of the alreadyallocated gate via a GATEMODIFY command. When complete, the newdestination information is passed to the BTI_(O) via a TRANSFER message.GATEMODIFY and TRANSFER are identical to the messages used for 3-waycalling and for call transfer. After resources are reserved for thiscall, BTI_(O) sends a RING command, and the response is either RINGBACK(if the new destination is onhook and now ringing) or CONNECT (if thenew destination is ready now). The latter would typically be the casewithin interactive voice response systems. After the CONNECT message,the resources are committed and the communication path is opened.

FIG. 22 shows the call flow for Call Forwarding—No Answer when the BTIis unavailable. This flow is identical to FIG. 18: Call Forwarding—AllCalls/BTI Unavailable Call Flow.

8.3.2 Caller ID/Calling Name Delivery

The following describes two alternatives for implementing CallerID/Calling Name Delivery with embodiments of the present invention.

The first is to have BTI_(T) request caller ID information upon receiptof the SETUP from the GC_(T). This request is sent to GC_(T), whichrecognizes the Caller ID flag and checks if the customer line hassubscribed for Caller ID/Calling Name services. GC_(T) returns the phonenumber (E.164_(o)) and the Calling Name (CN_(o)) of the call originator.Subsequently, BTI_(T) returns a SETUPACK as usual. If the subscriber atBTI_(T) subscribes to services such as Anonymous Call Rejection or CallScreening, then the SETUPACK may not be returned by BTI_(T). Finally,when BTI_(T) rings the phone (assuming it is a simple “black phone” withthe traditional Caller ID box), then the Caller ID and Calling Name arepresented to the Caller ID box between the 1^(st) and 2^(nd) ring. Ifthe user's telephone is more intelligent, this information may bepresented as a message that is interpreted and displayed. FIG. 23 showsthe call flow for this alternative.

1. Another alternative for implementing Caller ID/Calling Name Deliveryis to have GC_(T) check if BTI_(T) subscribes to the service on receiptof every call. If so, the caller's phone number (E.164_(o)) and theCalling name (CN_(o)) are sent in the SETUP message to BTI_(T) on everyincoming call. The BTI can either accept (SETUPACK) or reject(SETUPNACK) the call based upon E.164_(o) and CN_(o). This alternativedoes not require additional messaging between GC_(T) and BTI_(T) forachieving Caller ID/Calling Name Delivery services.

8.3.3 Call Waiting

FIG. 24 showsw a call flow for Call Waiting, accordeing to an embodimentof the present invention. Initially, there is a call in progress betweenthe BTI_(O1), and BTI_(T). A second call from BTI_(O2) to BTI_(T) isestablished up to the point of reserving access and backbone bandwidth.BTI_(O2) reserves the channel as normal, but BTI_(T) uses a RERESERVEmessage to indicate that it does not need a new access reservation, butjust needs to associate the new gate (GID_(T2)) in the ER with theexisting access reservation for gate (GID_(T1)). “RING” and “RINGBACK”messages are exchanged between the new BTI_(O2) and BTI_(T). BTI_(T) nowinserts a “call waiting tone” into the original call in progress toindicate to the user that there is a second incoming call. When the userdoes a “flash-hook”, then BTI_(T) sends a HOLD message to BTI_(O1) andreceives an acknowledgment for this message. Subsequently, BTI_(T)completes the call to BTI_(O2) by sending a CONNECT message. Instead ofhaving another allocation of resources for BTI_(T) for this new call, wego through a reallocation of existing resources. The BTI_(T) sends aRECOMMIT message with the Gate IDs of the two calls (GID_(T1) andGID_(T2)) so that ER_(T) may reallocate the resources from the first tothe second call. In addition, a new CALLSTART event is sent to thebilling server. When BTI_(O1) gets the HOLD message, it requests ER_(O1)to suspend allocation of its resources on the MCNS channel using theHOLD message until a future COMMIT message is sent from BTI_(O1).BTI_(O1) sends periodic KEEPALIVE message both to ER_(O1) and BTI_(T) toensure that the bandwidth is not reallocated to other calls.

8.3.4 Three-Way Calling

8.3.4.1 Three-Way Calling—Bridging in BTI

FIG. 25 shows the call flow for the simple Three-Way Calling alternativewith bridging in BTI_(O). In the flow, a second call is set up as atotally new call using separate resources in BTI_(O), the accessnetwork, and the backbone network. When the customer wants to completethe three-way call (indicated by the second flash-hook), BTI_(O) bridgesthe calls together.

This section describes the use of a bridge located on a server insidethe network. FIG. 26 illustrates the first steps of a three-way call.The customer starts with an existing call, either one he or she placedor one that he or she received. By flashing the switchhook, that call isplaced on hold. A HOLD message is sent to the destination indicatingthis change, and HOLDACK is sent in response. Both ends then informtheir ERs that the isochronous transmission will be temporarily halted,but to keep the committed resources, via the HOLD message to the ER.Periodic KEEPALIVE messages are sent to each end and the ERs toaccomplish this.

BTI_(O) then plays the originator dialtone, and receives the full E.164address of the additional party to call. This new call proceeds as shownin FIG. 6 for normal call setup. At the point of the resourcereservation exchange, ER_(O) has allocated two gates (the original onewith the parameters of the first call, and the new one with parametersfor this call), upstream access resources are reserved for one call, andthe backbone has reserved resources for both of the calls. When thethird party answers, the second call is established using the resourcesreserved for GID_(O2). This state is identical to that of call-waiting,when one call is on hold and the subscriber is talking on a second call.However, since the subscriber initiated the second call, instead ofreceiving that call, the later hookflash commands a three-way callinstead of a switch back to the first conversation.

FIG. 27 shows the sequence of signaling messages exchanged in theconversion of two separate calls into one three-way call. BTI_(O)allocates a conference bridge by creating a third connection to aspecial network server. The bridge server will take an arbitrary numberof input streams and generate an output stream for each; each output isthe sum of all inputs except for the contribution from the correspondinginput. When the number of inputs exceeds a small number (e.g. 3), thebridge does silence detection on each input to reduce the accumulatednoise.

Once the host establishes the connection to the bridge, each of theparticipants of the three-way call need to be informed of the newdestination, and need to have their gates modified appropriately. Thisfunction is identical to that done for Call Forwarding with No Answer,and involves BTI_(O) sending a REDIRECT message for each existingconnection.

The REDIRECT function involves two steps. First is a GATEMODIFY messageto the ER modifying the parameters of the gate. This message includesthe new destination address for data packets, as well as new billinginformation. Second is a TRANSFER message to the BTI, telling it toswitch to a new destination for sending and receiving packets. Beforeacknowledging this message, the BTI performs a resource reservationexchange with the indicated endpoint (in this case, the bridge) toensure network resources are available.

The GATEMODIFY message sent to the ER includes charging information ($).Calls from each endpoint to the bridge involve split-charging; theoriginator of the call pays only for the equivalent call to his/herdialed destination, and the party making the three-way call pays for theextra segment to the bridge. This is similar to that done for CallForwarding.

The GATEMODIFY message sent to the ER also includes a BillingIdentifier, BID. This unique identifier is given to all of the ERsinvolved in the three-way call, so that all billing records produced canbe matched later. The BID used for the call is the unique ID assignedfor the BTI_(O) to Bridge connection.

The TRANSFER message sent to the BTI includes updated CI_(B)information, encrypted by the local GC. This information replaces theprevious CI information. CI_(B) contains sufficient information to allowone of the participants in this 3-way call to add another party andallocate an additional bridge; use of this CI_(B) for a return-call orfor call-trace will result in errors.

It is possible for one of the participants in a 3-way call, who alsosubscribes to the 3-way calling service, to add another party. The callflow is identical to FIG. 27, except that one of the endpoints is not aBTI but rather the first Bridge. The Bridge handles TRANSFER messages inthe same way as the BTI, allowing this service to cascade.

This sequence assumes the Bridge is located within the network, and doesnot need global address or gates to be allocated. GC_(O) is identifiedas the Gate Controller serving the bridge, and there is no ER and noneed for upstream scheduling of access lines. If the bridge were insteadlocated outside of the network, then additional exchanges would berequired to establish the gates and allocation of upstream bandwidth.These exchanges would be identical to those for normal callestablishment.

There are two separate cases for hangup sequences. If the originator ofthe 3-way call hangs up, it sends the RELEASE message to its local ERand a HANGUP message to the bridge. The bridge, sends HANGUP messages tothe other two legs of the call and also GATECLOSE messages to their ERs.This sequence is shown in FIG. 28.

If a participant in the 3-way call disconnects, it is desired that thebridge be released and the call revert back to a normal two-party call.FIG. 20 shows the sequence of messages needed to perform this function.The Bridge receives a HANGUP message from a participant BTI, and sends aSPLICE message to its GC, giving the connection information (CI) for thetwo call legs to be spliced together.

The GCs inform the ERs, via a GATEMODIFY command, of the new destinationof the data packets, and inform the BTIs, via a TRANSFER command, of thenew destination. In case of errors, such as when the resourcereservation exchange fails to allocate backbone bandwidth for the directconnection, the bridge can stay involved in the call with the tworemaining parties.

8.3.5 Call Transfer

There are two different call transfer services. Call Transfer WithConsultation is a service very similar to Three-Way Calling except thatwhen the originator of the three-way call disconnects, the remaining twoparties can still talk. Call Transfer Without Consultation is similar toCall Forwarding, except the forwarding can be done after a call isestablished.

8.3.5.1 Call Transfer with Consultation

Call Transfer With Consultation is very similar to Three-Way Callingexcept that when the customer (or host) hangs up the phone, the callbetween the two participants can continue. Also billing continues as ifboth legs of the call are still in place.

Most of the call flows for setting up a Call Transfer With Consultationare identical to those for Three-Way Calling (FIG. 26, FIG. 27, and FIG.29). The only call flow that is different is when a host disconnects.FIG. 30 shows the call flow for Call Transfer With Consultation servicewhen the host disconnects. As with Three-Way Calling, the call revertsto a simple two-way call between the two participants. However, thebilling for the call continues as if it is a three-way call. For theCall Transfer With Consultation call flow, the following events haveproceeded the hangup of the host:

1) BTI_(T1) has originated a call to BTI_(O) and billing records(BID_(T1/O)) for this leg of the call are being generated by ER_(T1).

2) BTI_(O) has put BTI_(T1) on hold and set up a new call to BTI_(T2).The billing records (BID_(O/T2)) for this leg of the call are beinggenerated by ER_(O).

3) BTI_(O) has joined the two legs of the call into a three-way callusing a network bridge.

At the point when the host hangs up, the gate at the host's edge router(ER_(O)) is closed and billing associated with that gate (BID_(O/T2)) isterminated. GC_(O) retrieves the information associated with thisbilling record (including the globally unique BID) from ER_(O) using theGATEINFO request and transfers the billing information to one of theparticipant's ERs. The participant ER that receives this information(ER_(T2) in the call flow), generates a new billing record for the legassociated with BID_(O/T2). During bill processing, the two billingrecords for BIDO_(O/T2) are associated using the unique BID so the callcan be billed properly.

8.3.5.2 Call Transfer without Consultation

As shown in FIG. 31, Call Transfer Without Consultation is very similarto Call Forwarding—No Answer.

8.3.6 Return Call

It is possible for GC_(O) to implement the return call service bystoring the number of the most recent incoming call (caller id) in theGate Controller, and then returning the call on a SETUP request.However, this requires the Gate Controller to retain state associatedfor every telephone. It would be desirable to allow the end-system(e.g., BTI) to retain this state, simplifying the Gate Controller.Unfortunately, if the incoming call was from a subscriber that hasblocked caller id, it is important to keep the caller id informationprivate, hence it cannot be made available to the end-system.

The solution is for the GC to send the caller id information to the BTIin a digitally signed and encrypted form, with every SETUP request. Whena user dials the *69 code to activate the return call service, BTI_(O)includes the encrypted information in the SETUP request to GC_(O). IfGC_(O) successfully decrypts and validates the information, and thecustomer subscribes to Return Call service, it returns the call as ifprocessing a normal SETUP request to the number associated with the mostrecent incoming call.

What is claimed is:
 1. A method for use in a packet-carryingcommunication network in which calls originating from respectiveoriginating interface units are routed through a routing entity of saidnetwork, the method comprising responsive to call setup requestsoriginating from the originating interface units, establishingparameters for said calls on a call-by-call basis, and causing at leastone of said established parameters to be stored in said routing entity,said routing entity operating to ensure that access to resources of saidnetwork is consistent with said at least one of said stored parameters,wherein said routing entity is a network edge device.
 2. The inventionof claim 1 wherein said network edge device is a packet router.
 3. Theinvention of claim 1 wherein said network edge device is a bridge. 4.The invention of claim 1 wherein said originating interface units areconnected to one end of an access network and said network edge deviceis connected to the other end of said access network.
 5. The inventionof claim 1 wherein the quality of service for at least ones of saidcalls is determined by at least one of the parameters established forthose calls.
 6. The invention of claim 1 wherein the parametersestablished for a call include transmission priority.
 7. The inventionof claim 1 wherein the parameters established for a call includeoperation, policy and traffic parameters.
 8. The invention of claim 1wherein said parameters established for a call are established by a gatecontroller, said gate controller thereupon communicating thoseparameters to said routing entity, said gate controller being an entityof said network through which calls are not routed.
 9. The invention ofclaim 1 further comprising establishing a gate for said each call atsaid network edge device, said gate being a call-admission controlmechanism for a call defined at least in part by the parametersestablished for the call.
 10. The invention of claim 9 wherein theparameters established for a call are established by a gate controllerthat communicates with said originating interface units.
 11. A methodfor use in a packet-carrying communication network in which callsoriginating from respective originating interface units are routedthrough a routing entity of said network, the method comprising:responsive to call setup requests originating from the originatinginterface units, establishing parameters for said calls on acall-by-call basis, and causing at least one of said establishedparameters to be stored in said routing entity, said routing entityoperating to ensure that access to resources of said network isconsistent with said at least one of said stored parameters, wherein atleast one of said parameters established for a call controls at leastone of: bounded packet loss and latency.
 12. A method for use in apacket-carrying communication network in which calls originating fromrespective originating interface units are routed through a routingentity of said network, the method comprising: responsive to call setuprequests originating from the originating interface units, establishingparameters for said calls on a call-by-call basis, and causing at leastone of said established parameters to be stored in said routing entity,said routing entity operating to ensure that access to resources of saidnetwork is consistent with said at least one of said stored parameters,wherein the parameters established for a call include at least one of:packet size and inter-packet interval.
 13. A method for use in apacket-carrying communication network in which calls originating fromrespective originating interface units are routed through a routingentity of said network, the method comprising: responsive to call setuprequests originating from the originating interface units, establishingparameters for each of said calls on a call-by-call basis, the qualityof service for said each call being determined by at least one of theparameters established for that call, causing at least one of saidestablished parameters to be stored in said routing entity, receiving,at said routing entity, packets for said each call from the respectiveoriginating interface unit, said routing entity routing said packets tosaid network and said routing entity utilizing said at least one of saidparameters to control admission of said packets into said network insuch a way as to provide a quality of service for said call that is nogreater than a quality of service previously authorized for that call.14. The invention of claim 13 wherein said at least one of theparameters is received by said routing entity from a gate controllerthrough which said calls are not routed.
 15. The invention of claim 14wherein said parameters established for said each call and stored atsaid routing entity include billing parameters for that call.
 16. Theinvention of claim 15 further comprising tracking resource usage at saidrouting entity for said each call.
 17. The invention of claim 14 whereinsaid parameters established for said each call and stored at saidrouting entity include at least one of: a source network address and adestination network address.
 18. The invention of claim 14 wherein saidnetwork edge device is a bridge.
 19. The invention of claim 13 whereinsaid routing entity is a network edge device.
 20. The invention of claim19 wherein said network edge device is a packet router.
 21. Theinvention of claim 19 wherein said originating interface units areconnected to one end of an access network and said network edge deviceis connected to the other end of said access network.
 22. The inventionof claim 13 wherein at least one of said parameters for said each callcontrols its bandwidth.
 23. The invention of claim 13 wherein theparameters established for said each call that determine its quality ofservice include transmission priority.
 24. The invention of claim 13wherein the parameters established for said each call include operation,policy and traffic parameters.
 25. The invention of claim 13 whereinsaid parameters for said each call are used in a gate established forsaid each call at said network edge device, said gate being acall-admission control mechanism for said each call defined at least inpart by said parameters established for that call.
 26. A method for usein a packet-carrying communication network in which calls originatingfrom respective originating interface units are routed through a routingentity of said network, the method comprising: responsive to call setuprequests originating from the originating interface units, establishingparameters for each of said calls on a call-by-call basis, the qualityof service for said each call being determined by at least one of theparameters established for that call, causing at least one of saidestablished parameters to be stored in said routing entity, receiving,at said routing entity, packets for said each call from the respectiveoriginating interface unit, said routing entity routing said packets tosaid network and said routing entity utilizing said at least one of saidparameters to control admission of said packets into said network insuch a way as to provide a quality of service for said call that is nogreater than a quality of service previously authorized for that call,wherein the parameters established for said each call that determine itsquality of service include packet size and inter-packet interval. 27.Apparatus for use in a packet-carrying communication network in whichcalls originating from respective originating interface units are routedthrough a routing entity of said network, the apparatus comprising:means for establishing parameters for each of said calls on acall-by-call basis in response call setup requests originating from theoriginating interface units, and means for causing at least one of saidestablished parameters to be stored in said routing entity, said routingentity being a network edge device, whereby said routing entity is ableto operate in such a way as to ensure that access to resources of saidnetwork during said each call is consistent with said at least one ofsaid stored parameters.
 28. The invention of claim 27 wherein theparameters established for at least ones of said calls include at leastone of: a source network address and a destination network address. 29.The invention of claim 27 wherein the quality of service for at leastones of said calls is determined by at least one of the parametersestablished for those calls.
 30. The invention of claim 29 wherein saidparameters that determine quality include transmission priority.
 31. Theinvention of claim 27 wherein the parameters established for said eachcall include operation, policy and traffic parameters.
 32. The inventionof claim 27 wherein said apparatus is a gate controller not adapted toroute packets during said calls.
 33. The invention of claim 32 whereinsaid means for causing at least one of said established parameters to bestored in said routing entity comprises means for establishing a gatefor said each call at said routing entity, said gate being acall-admission control mechanism for said each call defined at least inpart by said parameters established for the call.
 34. Apparatus for usein a packet-carrying communication network in which calls originatingfrom respective originating interface units are routed through a routingentity of said network, the apparatus comprising: means for establishingparameters for each of said calls on a call-by-call basis in responsecall setup requests originating from the originating interface units,and means for causing at least one of said established parameters to bestored in said routing entity, wherein a quality of service for at leastparticular ones of said calls is determined by at least one of theparameters established for said particular ones of said calls, whereinat least one of said parameters established for said each call controlsat least one of a) bounded packet loss and b) latency, of said eachcall.
 35. Apparatus for use in a packet-carrying communication networkin which calls originating from respective originating interface unitsare routed through a routing entity of said network, the apparatuscomprising: means for establishing parameters for each of said calls ona call-by-call basis in response call setup requests originating fromthe originating interface units, and means for causing at least one ofsaid established parameters to be stored in said routing entity, whereina quality of service for at least particular ones of said calls isdetermined by at least one of the parameters established for saidparticular ones of said calls, and wherein said parameters thatdetermine quality of service include packet size and inter-packetinterval.
 36. A packet routing device for use in a packet-carryingcommunication network in which calls originating from respectiveoriginating interface units are routed through said packet routingdevice, the packet routing device comprising: means for receiving andstoring packet parameters that were established on a call-by-call basisresponsive to call setup requests originating from the originatinginterface units, and means for routing, to said network, packets thatwere received for each call from the respective originating interfaceunit, said packet routing device being adapted to utilize said at leastone of said packet parameters to control admission of said packets intosaid network.
 37. The invention of claim 36 wherein said means forreceiving and storing is adapted to receive and store at said routingentity billing parameters for said calls.
 38. The invention of claim 37further comprising means for tracking resource usage at said routingentity for said each call.
 39. The invention of claim 36 wherein saidmeans for receiving and storing is adapted to receive and storeparameters at said routing entity that include at least one of: a sourcenetwork address and a destination network address.
 40. The invention ofclaim 36 wherein said packet routing device is a packet router.
 41. Theinvention of claim 36 wherein said packet routing device is a bridge.42. The invention of claim 36 wherein at least one of said parametersfor said each call controls its bandwidth.
 43. The invention of claim 36wherein the parameters established for said each call includetransmission priority.
 44. The invention of claim 36 wherein theparameters established for said each call include operation, policy andtraffic parameters.
 45. The invention of claim 36 wherein saidparameters for said each call are used in a gate established for saideach call at said packet routing device, said gate being acall-admission control mechanism for said each call defined at least inpart by said parameters established for the call.
 46. A packet routingdevice for use in a packet-carrying communication network in which callsoriginating from respective originating interface units are routedthrough said packet routing device, the packet routing devicecomprising: means for receiving and storing parameters that wereestablished for said calls on a call-by-call basis responsive to callsetup requests originating from the originating interface units, andmeans for routing, to said network, packets that were received for eachcall from the respective originating interface unit, said packet routingdevice being adapted to utilize said at least one of said parameters tocontrol admission of said packets into said network, wherein theparameters established for said each call include packet size andinter-packet interval.
 47. A method for use in a packet-carryingcommunication network in which a call originating from an originatinginterface unit is routed through a packet routing entity of saidnetwork, the method comprising: receiving a call setup requestoriginating from the originating interface unit, the call setup requestincluding at least an identification of a terminating location,subsequent to receipt of the call setup request, establishingquality-of-service parameters for the call, and causing at least one ofsaid established parameters to be stored in said packet routing entity,and responsive to the call setup request, establishing an end-to-endconnection between the originating interface unit and the terminatinglocation, said packet routing entity operating during the call to ensurethat access by packets to resources of said network is consistent withsaid at least one of said stored parameters.
 48. The invention of claim47 wherein said routing entity is a network edge device.
 49. Theinvention of claim 48 wherein said network edge device is a packetrouter.
 50. The invention of claim 48 wherein the originating interfaceunit is connected to one end of an access network and said network edgedevice is connected to the other end of said access network.
 51. Theinvention of claim 48 further comprising establishing a gate for thecall at said network edge device, said gate being a call-admissioncontrol mechanism for the call defined at least in part by theparameters established for the call.
 52. The invention of 51 wherein theparameters established for the call are established by a gate controllerthat communicates with said originating interface unit.
 53. Theinvention of claim 47 wherein the parameters established for the callinclude at least one of: a source network address and a destinationnetwork address.
 54. The invention of claim 47 wherein the quality ofservice for the call is determined by at least one of the storedparameters.
 55. The invention of claim 47 wherein the parametersestablished for the call include at least one of: packet size andinter-packet interval.
 56. The invention of claim 47 wherein theparameters established for the call include transmission priority. 57.The invention of claim 47 wherein the parameters established for thecall include operation, policy and traffic parameters.
 58. The inventionof claim 47 wherein said parameters established for a call areestablished by a gate controller, said gate controller thereuponcommunicating those parameters to said routing entity, said gatecontroller being an entity of said network through which calls are notrouted.
 59. The invention of claim 58 wherein said routing entity is anetwork edge device.